A block is placed at the top of a frictionless inclined plane with angle 30 degrees and released. The incline has a height of 15 m and the block has mass 2 kg. In the above problem the speed of the block when it reaches the bottom of the incline is 8.3 m/s 17 m/s 25 m/s 30 m/s

Answers

Answer 1

Answer:

The speed of the block when it reaches the bottom is 17 m/s.

(b) is correct option.

Explanation:

Given that,

Height = 15 m

Mass = 2 kg

We need to calculate the speed of the block when it reaches the bottom

Using conservation of energy

[tex]mgh=\dfrac{1}{2}mv^2[/tex]

[tex]v^2=2gh[/tex]

[tex]v=\sqrt{2gh}[/tex]

Where, g = acceleration due to gravity

h = height

Put the value into the formula

[tex]v=\sqrt{2\times9.8\times15}[/tex]

[tex]v=17\ m/s[/tex]

Hence, The speed of the block when it reaches the bottom is 17 m/s.


Related Questions

A mass of 156.7g of Helium gas at an initial temperature of 35.73°C and at an initial absolute pressure of 3.55 atm undergoes an isothermal expansion until its volume increases by a factor of 1.75. (a) What is the final pressure? (b) How much work is done on the gas? (c) How much heat does the gas absorb? (d) What is the change in the total internal energy of the gas? (a) Pa Answer part (a) (b) Joules Answer part (b) Joules Joules Answer part (C) Answer part (d) (d) Submit

Answers

Answer:

Explanation:

Moles of helium ( n ) = 156.7 / 4 = 39.175

Temperature T₁ = 35.73 +273 = 308.73 K

Volume V₁ = V

Pressure P₁ = 3.55 atm

V₂ =1.75 V

a ) For isothermal change

P₁ V₁ = P₂V₂

P₂ = P₁ V₁ / V₂

= 3.55 X V / 1.75 V

= 2.03 atm.

b ) Work done by the gas = nRT ln(V₂/V₁)

= 39.175 X 8.321 X 308.73 X ln 1.75

= 56318.8 J

Work done on the gas = - 56318.8 J

c ) Since there is no change in temperature , internal energy of gas is constant

Q = ΔE + W

ΔE  = 0

Q = W

Work done by gas = heat absorbed

heat absorbed = 56318.8 J

d ) Change in the internal energy of gas is zero because temperature is constant.

A tennis ball is hit straight up at 20 m/s from the edge of a sheer cliff. Some time later, the ball passes the original height from which it was hit. (Ignore the effects of air resistance.) (a) How fast is the ball moving at that time? m/s (b) If the cliff is 50 m high, how long will it take the ball to reach the ground level? s (c) What total distance did the ball travel? m

Answers

Final answer:

The speed of the ball when passing its original height on its way down is 20 m/s. The time it takes to reach the ground level is 3.19 seconds. The ball travels a total distance of 70 meters.

Explanation:

The motion of the tennis ball can be analyzed by using the principles of Physics, particularly the laws of motion and the concept of gravity.

(a) The ball will have the same speed when it passes its original height on its way down, which is 20 m/s. This is based on the principle of conservation of energy. Since air resistance is ignored, the speed when it passes the original height on its way down should be the same as its initial speed.

(b) Calculating the total time it takes the ball to reach the ground involves the formula for time in free fall, which is t = sqrt(2h/g), wherein h is the height and g is the gravity. Thus plug in the values: t = sqrt((2*50)/9.8) = 3.19 seconds.

(c) The total distance traveled by the ball includes it going up and falling back down. The ball rises to a height of 20 m/s before falling from that height plus an additional height corresponding to the height of the cliff, total distance is 70 meters.

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A flat circular plate of copper has a radius of 0.131 m and a mass of 98.6 kg. What is the thickness of the plate? Answer in units of m.

Answers

Answer:

h = 0.204 m

Explanation:

given data:

radius r = 0.131 m

mass m = 9.86 kg

density of copper = 8960 kg/m3

we knwo that density is given as

[tex]\rho = \frac{mass}{volume}[/tex]

[tex]volume = \pi * r^2 h[/tex]

[tex]density  =  \frac{ mass}{\pi * r^2 h}[/tex]

[tex]h = \frac{ mass}{\pi * r^2 * density}[/tex]

putting all value to get thickness value

[tex]h = \frac{ 98.6}{ \pi 0.131^2*8960}[/tex]

h = 0.204 m

Two students are having a discussion about the Moon. The first student claims that we always see only one side of the Moon and that the other side is the "dark side." This student also further asserts that the dark side of the Moon is always dark. The second student disagrees with the first and claims that since the Moon is rotating, we see both sides of the Moon. Which student do you agree with and why? Why is the other student wrong?

Answers

Answer:

We should only agree with the first statement of the first student but not with the second part of his statement. While as the statement of the other student is completely wrong.

Explanation:

The earth and the moon are locked in a process known as tidal locking. Tidal locking occurs when any object which revolves around other object takes the same amount of time to rotate around it's own axis as it takes to revolve around the planet.

This is exactly the case with moon and the earth system ,the moon is tidally locked with earth thus we cannot see the other side of the moon but this side is not dark as claimed by the first student but this side of the moon is also illuminated by the sunlight as the face of moon that we are able to see.

The second student is wrong as we cannot see the other side of moon from earth.

Final answer:

The Moon is in synchronous rotation with Earth, which means the same side, the near side, always faces Earth. The far side, incorrectly called the 'dark side,' is not perpetually dark but simply not visible from Earth and receives sunlight just like the near side.

Explanation:

The student who claimed that we always see only one side of the Moon is correct; however, their assertion that the other side is the "dark side" and always dark is incorrect. This is because the Moon is in synchronous rotation with Earth—it rotates on its axis in the same amount of time it takes to orbit Earth. Because of this, only one hemisphere, the near side, is visible from Earth, while the other hemisphere, the far side, remains out of view.

The idea that the far side is the "dark side" is a misconception; it receives sunlight just as the near side does, only at different times during the Moon's orbit. The term "dark side" only means that it's the side not visible from Earth. As the Moon revolves around Earth, different parts experience day and night, similar to how the Sun rises and sets on Earth. Therefore, the "dark side" is not perpetually dark; it simply refers to the lunar face we do not see that is also subject to changing illumination by the Sun.

In summary, the correct understanding is that the same side of the Moon always faces Earth, not because it doesn't rotate, but because it has a synchronous orbit with Earth, and the use of the term "dark side" is a misnomer since all parts of the Moon experience both sunlight and darkness at different times.

A water gun is fired horizontally from a 4 meter tall hill and lands 7 meters from the base of the hill. (a) How long is the water in the air? (b) What is the initial velocity of the water?

Answers

Answer:

(a) 0.9 s

(b) 7.78 m/s

Explanation:

height, h = 4 m

Horizontal distance, d = 7 m

Let it takes time t to reach the ground and u be the initial velocity of the jet.

(a) Use second equation of motion in vertical direction

[tex]s = ut + \frac{1}{2}at^{2}[/tex]

In vertical direction, uy = 0 m/s, a = g = - 9.8 m/s^2, h = - 4 m

By substituting the values, we get

[tex]-4 = 0 - \frac{1}{2}\times 9.8\times t^{2}[/tex]

t = 0.9 second

Thus, the time taken by water jet in air is 0.9 second.

(b) Use

Horizontal distance = horizontal velocity x time

d = u t

7 = u x 0.9

u = 7.78 m/s

Thus, the initial velocity of water jet is 7.78 m/s.

Final answer:

The duration the water is in the air is found using the formula for the motion under gravity, which depends on the vertical distance and the acceleration due to gravity. After finding the time, the initial velocity of the water is calculated using the horizontal distance and the fraction of time the water was in motion.

Explanation:

To determine how long the water is in the air (a), and the initial velocity of the water (b) when a water gun is fired horizontally from a hill, we can use the principles of projectile motion. The time a projectile is in the air is solely determined by its vertical motion. Since the water gun is fired horizontally, it has an initial vertical velocity of 0 m/s.

For part (a), the time (t) it takes for the water to reach the ground can be calculated using the formula for the motion under gravity, which is y = 0.5 * g * t2, where y is the vertical distance (4 meters in this case) and g is the acceleration due to gravity (approximated to 9.81 m/s2). Solving for t gives us the time the water is in the air.

For part (b), once we have the time, we can use the horizontal distance (7 meters) to find the initial velocity (v0) using the formula x = v0 * t. This provides the initial horizontal velocity of the water gun's jet. The overall process involves solving for time first and then using that time to find the initial velocity.

The tallest volcano in the solar system is the 23 km tall Martian volcano, Olympus Mons. An astronaut drops a ball off the rim of the crater and that the free fall acceleration of the ball remains constant throughout the ball's 23 km fall at a value of 3.5 m/s^2. (We assume that the crater is as deep as the volcano is tall, which is not usually the case in nature.) Find the time for the ball to reach the crater floor. Answer in units of s. Find the magnitude of the velocity with which the ball hits the crater floor. Answer in units of m/s.

Answers

The magnitude of the velocity with which the ball hits the crater floor is approximately 401.24 m/s.

Let's convert the height to meters:

Height = 23 km

= 23,000 m

Now we can use the kinematic equation to find the time it takes for the ball to reach the ground:

[tex]h=\frac{1}{2}gt^2[/tex]

Where: h = height (23,000 m)

g = acceleration due to gravity (3.5 m/s²)  

t = time

Solving for t:

[tex]t=\sqrt{\frac{2h}{g}}[/tex]

Plug in the values:

[tex]t=\sqrt{\frac{2 \times 23000}{3.5}}[/tex]

t=114.64 s

So, the time for the ball to reach the crater floor is approximately 114.64 seconds.

Now calculate the magnitude of the velocity with which the ball hits the crater floor.

We can use the following kinematic equation:

v=gt

Where:

v = final velocity

g = acceleration due to gravity (3.5 m/s²)

t = time (114.64 s)

v=3.5×114.64

v=401.24 m/s

Hence, the magnitude of the velocity with which the ball hits the crater floor is approximately 401.24 m/s.

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Final answer:

The time it would take for the ball to hit the crater floor would be approximately 360.8 seconds, and the velocity it would hit the floor with would be approximately 1262.8 m/s.

Explanation:

To calculate the time it takes for the ball to reach the crater floor, we use the equation of motion d = 1/2gt^2, where 'd' represents the distance, 'g' represents the acceleration due to gravity, and 't' represents time. Here, the distance is 23,000m (converted from km to m), and the acceleration due to gravity is 3.5 m/s^2. By solving for 't' in this equation, we get t = sqrt(2d/g) = sqrt((2*23000)/3.5) = approx. 360.8s.

To calculate the magnitude of the final velocity as the ball hits the crater floor, we use the equation v = gt, where 'v' is the final velocity and 't' is the amount of time it has fallen. Plugging in the values we have for 'g' and 't', we get v = 3.5 * 360.8s = approx. 1262.8 m/s

Therefore, the time it would take for the ball to hit the crater floor would be approximately 360.8 seconds, and the velocity it would hit the floor with would be approximately 1262.8 m/s.

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Show that any three linear operators A, B, and Ĉ satisfy the following (Ja- cobi) identity (10 pt) [[A, B] Ĉ] + [[B,C), A] + [[C, A, B) = 0

Answers

Answer:

Three linear operators A,B, and C will satisfy the condition [tex][[A, B],C] + [[B,C), A] + [[C, A], B] = 0[/tex].

Explanation:

According to the question we have to prove.

[tex][[A, B],C] + [[B,C), A] + [[C, A], B] = 0[/tex]

Now taking Left hand side of the equation and solve.

[tex][[A, B],C] + [[B,C), A] + [[C, A], B][/tex]

Now use commutator property on it as,

[tex]=[A,B] C-C[A,B]+[B,C]A-A[B,C]+[C,A]B-B[C,A]\\=(AB-BA)C-C(AB-BA)+(BC-CA)A-A(BC-CB)+(CA-AC)B-B(CA-AC)\\=ABC-BAC-CAB+CBA+BCA-CAB-ABC+ACB+CAB-ACB-BCA+BAC\\=0[/tex]

Therefore, it is proved that [tex][[A, B],C] + [[B,C), A] + [[C, A], B] = 0[/tex].

An object moving with constant acceleration changes its speed from 20 m/s to 60 m/s in 2.0 s. What is the acceleration? (b) How far did it move in this time?

Answers

Answer:

acceleration, a = [tex]20 m/s^{2}[/tex]

distance, d = 80 m

Given:

Initial velocity of object, v = 20 m/s

Final velocity of object, v' = 60 m/s

Time interval, [tex]\Delta t = 2.0 s[/tex]

Solution:

(a) Acceleration is the rate at which velocity changes and constant acceleration is when the velocity changes by equal amount in equal intervals of time.

Thus

acceleration, a = [tex]\frac{v' - v}{\Delta t}[/tex]

a = [tex]\frac{60 - 20}{2.0} = 20 m/s^{2}[/tex]

(b) Now, the distance covered is  given by:

[tex]d = vt + \frac{1}{2}at^{2}[/tex]

[tex]d = 20\times 2.0 + \frac{1}{2}20\times 2^{2} = 80 m[/tex]

A squirrel runs along an overhead telephone wire that stretches from the top of one pole to the next. It is initially at position xi=3.37 mxi=3.37 m , as measured from the center of the wire segment. It then undergoes a displacement of Δx=−6.83 mΔx=−6.83 m . What is the squirrel's final position xfxf ?

Answers

Answer:

- 3.46 m

Explanation:

initial position, xi = 3.37 m

displacement, Δx = - 6.83 m

Let the final position is xf.

So, displacement = final position - initial position

Δx = xf - xi

- 6.83 = xf - 3.37

xf = 3.37- 6.83

xf = - 3.46 m

Thus, the final position of the squirrel is - 3.46 m.

An amplitude modulation transmitter radiates 10 KW power with the modulation percentage of 75 %. Find the magnitude of the carrier power?

Answers

Answer:

carrier power is 7.8 kW

Explanation:

given data

power = 10 kW

modulation percentage = 75 %

to find out

carrier power

solution

we will use here power transmitted equation that is

power = [tex]carrier power * ( 1+  \frac{modulation}{2})[/tex]   .................1

put here value in equation 1  we get carrier power

10 = [tex]carrier power *(1+ \frac{0.75}{2})[/tex]

carrier power = 7.8

so carrier power is 7.8 kW

At the instant the traffic light turns green, an automobile starts with a constant acceleration a of 2.20 m/s^2. At the same instant a truck, traveling with a constant speed of 8.50 m/s, overtakes and passes the automobile. (a) How far beyond the traffic signal will the automobile overtake the truck? (b) How fast will the automobile be traveling at that instant?

Answers

Answer:

a) d=65.7 m : The automobile overtake passes the truck at a distance of 65.7 m  from the traffic signal

b) vₐ=16.94m/s : Automobile  speed for t = 7.7s

Explanation:

When the car catches the truck, the two will have passed the same time (t) and will have traveled the same distance (d):

Automobile kinematics:

car moves with uniformly accelerated movement:

d = v₀*t + (1/2)a*t²

v₀ = 0 : initial speed  

d = (1/2)*a*t² Equation (1)

Truck kinematics:

Truck moves with constant speed:

d = v*t Equation (2)

Data:

a=2.20 m/s² : automobile acceleration

v= 8.50 m/s  ; truck speed

Equation (1) =Equation (2)

(1/2)*a*t²= v*t

(1/2)*2.2*t²= 8.5*t   We divide both sides of the equation by t:

1.1*t=8.5

t=8.5÷1.1

t=7.7 s

We replace t=7.7 s in the equation (2)

d=8.5*7.7

d=65.7 m

Automobile  speed for t = 7.7s

vₐ=v₀₊a*t

vₐ=o₊2,2*7.7

vₐ=16.94m/s

A person is jumping off a bridge onto the top of a car that is passing underneath. Suppose that the top of the bridge is h=10 meters above the car and the car is moving at a constant speed of V=30 mi/h The person wants to land in the middle of the car. How far from the bridge should the car be when the person jumps. Express the equation in variables then numerically

Answers

Answer:

18.96 m

Explanation:

Height from person jump, h = 10 m

Let it takes time t to reach to the car.

Use second equation of motion

[tex]s = ut +0.5at^2[/tex]

Here, a  g = 10 m/s^2 , u = 0, h = 10 m  

By substituting the values, we get

10 = 0 + 0.5 x 10 x t^2

t = 1.414 s

The speed of car, v = 30 mi/h = 13.41 m/s

Distance traveled by the car in time t , d = v x t = 13.41 x 1.414 = 18.96 m

So, the distance of car from the bridge is 18.96 m as the man jumps.

A bowling ball encounters a 0.760-m vertical rise on
theway back to the ball rack, as the drawing illustrates.
Ignorefrictional losses and assume that the mass of the ball
isdistributed uniformly. The translational speed of the ballis 3.50
m/s at the bottom of the rise. Find the translationalspeed at the
top.

Answers

Answer:1.26 m/s

Explanation:

Given

translation speed of ball =3.5 m/s

Moment of inertia of ball about com [tex]I=\frac{2}{5}mr^2[/tex]

Initial Energy

[tex]E_i=\frac{1}{2}mu^2+\frac{1}{2}I\omega _i^2(\omega =\frac{u}{r})[/tex]

Final Energy

[tex]E_f=\frac{1}{2}mv^2+\frac{1}{2}I\omega _f^2+mgh[/tex]

Equating energy as no energy loss take place

[tex]E_i=E_f[/tex]

[tex]\frac{1}{2}mu^2+\frac{1}{2}I\omega _i^2=\frac{1}{2}mv^2+\frac{1}{2}I\omega _f^2+mgh[/tex]

[tex]\frac{1}{2}mu^2+\frac{1}{2}\times \frac{2}{5}mr^2\times \left ( \frac{u}{r}\right )^2=\frac{1}{2}mv^2+\frac{1}{2}\times \frac{2}{5}mr^2\times \left ( \frac{v}{r}\right )^2+mgh[/tex]

m term get cancel

[tex]\left ( \frac{u^2}{2}\right )+\left ( \frac{2u^2}{10}\right )=\left ( \frac{v^2}{2}\right )+\left ( \frac{2v^2}{10}\right )+gh[/tex]

[tex]\frac{7}{10}u^2=\frac{7}{10}v^2+gh[/tex]

[tex]v^2=3.5^2-\frac{10}{7}\times 9.81\times 0.76[/tex]

[tex]v=\sqrt{1.6}=1.26 m/s[/tex]

After catching the ball, Sarah throws it back to Julie. However, Sarah throws it too hard so it is over Julie's head when it reaches Julie's horizontal position. Assume the ball leaves Sarah's hand a distance 1.5 meters above the ground, reaches a maximum height of 8 m above the ground, and takes 1.619 s to get directly over Julie's head. What is the speed of the ball when it leaves Sarah's hand?

Answers

The speed of the ball when it leaves Sarah's hand is 8.2 m/s.

Given that;

The ball leaves Sarah's hand at a distance of 1.5 meters above the ground, reaches a maximum height of 8 m above the ground, and takes 1.619 s to get directly over Julie's head.

For the speed of the ball when it leaves Sarah's hand, use the equations of motion and consider the vertical motion of the ball.

Since the ball is thrown vertically upward and then comes back down, the time taken to reach the maximum height is half of the total time of flight.

Therefore, the time to reach the maximum height is,

t/2 = 1.619 s / 2.

So, the time to reach the maximum height is 0.8095 s.

Now, let's find the initial vertical velocity of the ball using the equation:

v = u + at

where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time.

At the maximum height, the final vertical velocity is 0 m/s because the ball momentarily stops.

The acceleration due to gravity, a, is -9.8 m/s² (negative because it acts downward).

Using the equation, we have:

0 m/s = u + (-9.8 m/s²) × 0.8095 s

Simplifying the equation:

u = 7.93 m/s

So, the initial vertical velocity of the ball is 7.93 m/s.

Since the ball travels in a parabolic path, the time taken to reach Julie's horizontal position is the same as the time taken to reach the maximum height, which is 0.8095 s.

Now, let's calculate the initial horizontal velocity of the ball, using the equation:

s = ut

where s is the horizontal distance travelled, u is the initial horizontal velocity, and t is the time.

The horizontal distance travelled is equal to the horizontal distance between Sarah and Julie, which we don't have.

However, since we are only interested in the initial horizontal velocity, we can assume that the horizontal distance travelled is equal to the distance between Sarah and Julie.

Therefore, s = 1.5 m.

Using the equation, we have:

1.5 m = u × 0.8095 s

u = 1.5 m / 0.8095 s

Calculating u, we find:

u ≈ 1.853 m/s

So, the initial horizontal velocity of the ball is 1.853 m/s.

Finally, the speed of the ball when it leaves Sarah's hand by combining the horizontal and vertical components of velocity using the Pythagorean theorem:

speed = √(horizontal velocity² + vertical velocity²)

speed = √(1.853 m/s)² + (7.951 m/s)²

Calculating the speed, we find:

speed ≈ 8.2 m/s

Therefore, the speed of the ball when it leaves Sarah's hand is 8.2 m/s.

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Final answer:

Using the kinematic equations for vertical motion, the initial speed of the ball Sarah threw is calculated to be approximately 7.94 m/s, based on the given maximum height and time to reach Julie's horizontal position.

Explanation:

To find the initial speed of the ball when it leaves Sarah's hand, we need to use the information about the ball's motion under gravity. We know it reaches a maximum height of 8 m and takes 1.619 s to get directly over Julie's head, starting from a height of 1.5 m.

The motion of the ball can be divided into two segments: ascending and descending. During the ascending part, the ball slows down due to gravity until it reaches its maximum height. In the descending part, it accelerates back down. Since the motion is symmetrical, the time to reach the maximum height is half of the total time, which is 1.619 s / 2 = 0.8095 s.

To find the initial velocity (v_i), we can use the kinematic equation for vertical motion:
v_i = v_f - g*t
where v_f is the final velocity (0 m/s at the maximum height), g is the acceleration due to gravity (9.81 m/[tex]s^2[/tex]), and t is the time to reach maximum height.

Plugging in the values, we get:
v_i = 0 m/s - (-9.81 m/[tex]s^2[/tex] * 0.8095 s) = 7.94 m/s
Therefore, the initial speed of the ball when it leaves Sarah's hand is about 7.94 m/s.

In a TV set, an electron beam moves with horizontal velocity of 4.3 x 10^7 m/s across the cathode ray tube and strikes the screen, 43 cm away. The acceleration of gravity is 9.8 m/s^2. How far does the electron beam fall while traversing this distance? Answer in units of m

Answers

Answer:

[tex]y=-4.9x10^{-16}m[/tex]

Explanation:

From the exercise we have initial velocity on the x-axis, the final x distance and acceleration of gravity.

[tex]v_{ox}=4.3x10^{7}m/s[/tex]

[tex]x=43cm=0.43m\\g=9.8m/s^{2}[/tex]

From the equation on moving particles we can find how long does it take the electron beam to strike the screen

[tex]x=x_{o}+v_{ox}t+\frac{1}{2}at^{2}[/tex]

Since [tex]x_{o}=0[/tex] and [tex]a_{x}=0[/tex]

[tex]0.43m=(4.3x10^{7}m/s)t[/tex]

Solving for t

[tex]t=1x10^{-8} s[/tex]

Now, from the equation of free-falling objects we can find how far does the electron beam fell

[tex]y=y_{o}+v_{oy}t+\frac{1}{2}gt^{2}[/tex]

[tex]y=-\frac{1}{2}(9.8m/s^{2})(1x10^{-8} s)=-4.9x10^{-16}m[/tex]

The negative sign means that the electron beam fell from its initial point.

A stone thrown off a bridge at 20 m above a river has an initial velocity of 12 m/s at an angle of 45° above the horizontal. What is the range of the stone? At what velocity does the stone strike the water?

Answers

Answer:

a) [tex]x=26m[/tex]

b) [tex]v_{y}=-21.5m/s[/tex]

Explanation:

From the exercise we know initial velocity, initial height

[tex]y_{o}=20m[/tex]

[tex]v_{o} =12m/s[/tex] [tex]\beta =45[/tex]º

a) The range of the stone is defined by how far does it goes. From the theory of free falling objects, we have:

[tex]y=y_{o}+v_{oy}t+\frac{1}{2}gt^{2}[/tex]

The stone strike the water at y=0

[tex]0=20+12sin(45)t-\frac{1}{2}(9.8)t^{2}[/tex]

Solving for t, using the quadratic formula

[tex]t=-1.33s[/tex] or [tex]t=3.06s[/tex]

Since time can't be negative, the answer is t=3.06s

Now, we can calculate the range of the stone

[tex]x=v_{o}t=(12cos(45))m/s(3.06s)=26m[/tex]

b) We can calculate the velocity were the stone strike the water using the following formula  

[tex]v_{y}=v_{oy}+gt=12sin(45)m/s-(9.8m/s^{2})(3.06s)=-21.5m/s[/tex]

The negative sign indicates that the stone is going down

Answer:

(a) x= 26m

(b) vf= 23.15m/s  

Explanation:

Given data

h=20m

Ɵ=45°

to find

(a) range of stone=x=?

(b) velocity=vf=?

Solution

For part (a)

You need to solve for time first using

yf = yi + visinƟt + 1/2gt^2

0 = 20m + 12sin45t + 1/2(-9.8)t^2

and use the quadratic equation to solve for t

t = 3.064 sec

To solve for the distance traveled use

x = xi + vicosƟt + 1/2at^2 there is no acceleration in the x direction so that cancels

x = 12cos(45)(3.064)

x= 26m

For part(b)

For b I'm not sure if you what direction you want the final velocity in the x, y, or the direction its traveling so I'll just give all 3.

Theres no change in the velocity in the x direction so its just vfx = vixcosƟ = 12cos45 = 8.49m/s

For the y direction its vfy^2 = viy^2 + 2g(Δy)

vfy = sqrt((12sin(45))^2 + 2(-9.8)(0-20m)) = 21.54m/s

The velocity the direction the stone is traveling is vf = sqrt(vx^2 + vy^2) = sqrt(8.49^2 + 21.54^2)

vf= 23.15m/s

A red ball is thrown down with an initial speed of 1.2 m/s from a height of 25 meters above the ground. Then, 0.6 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 23.8 m/s, from a height of 0.8 meters above the ground. The force of gravity due to the earth results in the balls each having a constant downward acceleration of 9.81 m/s^2. A)What is the maximum height the blue ball reaches?
B)What is the height of the blue ball 1.8 seconds after the red ball is thrown?
C)How long after the red ball is thrown are the two balls in the air at the same height?

Answers

Answer:

A) The maximum height of the blue ball is 29.7 m above the ground.

B) The height of the blue ball after 1.8 s of throwing the red ball is 22.3 m

C) The balls are at the same height 1.41 s after the red ball is thrown

Explanation:

A) At maximum height, the velocity of the blue ball is 0 because for that instant, the ball does not go up nor down.

The equation for velocity for an accelerated object moving in a straight line is:

v = v0 + a*t

where

v = velocity.

v0 = initial velocity.

a = acceleration, in this case, it is the acceleration of gravity, g, 9.81 m/s².

t = time.

Then:

0 = v0 + g * t  (if the origin of the reference system is the ground, then g is negative)

0 = 23.8 m/s - 9.81 m/s² * t

-23.8 m/s / -9.81 m/s² = t

t = 2.43 s

With this time, we can calculate the position of the blue ball. The equation for position is:

y = y0 + v0 * t + 1/2 * g * t²

y = 0.8 m + 23.8 m/s * 2.43 s - 1/2 * 9.81 m/s² * (2.43 s)²

y = 29.7 m

the maximum height of the blue ball is 29.7 m above the ground.

B) 1.8 s after throwing the red ball, the blue ball was in the air for (1.8 s - 0.6) 1.2 s. Then, using the equation for the position of the blue ball:

y = 0.8 m + 23.8 m/s * 1.2 s - 1/2 * 9.81 m/s² * (1.2 s)² = 22.3 m

The height of the blue ball after 1.8 s of throwing the red ball is 22.3 m

C) Now, we have to find the time at which both positions are equal. Notice that the time of the blue ball is not the same as the time for the red ball. The time for the blue ball is the time of the red ball minus 0.6 s:

t blue = t red - 0.6 s

Then:

position red ball = position blue ball

 y0 + v0 * t + 1/2 * g * t² = y0 + v0 * (t- 0.6) + 1/2 * g * (t-0.6s)²

25 m + 1.2 m/s * t -1/2 * 9.81 m/s² * t² = 0.8 m + 23.8 m/s * (t-0.6 s) - 1/2 * 9.81 m/s² * (t-0.6 s)²

24.2 m + 1.2 m/s * t -4.91 m/s² * t² = 23.8 m/s * t - 14.28 m - 4.91 m/s² * (t-0.6 s)²

38.5 m - 22.6 m/s * t - 4.91 m/s² * t² = -4.91 m/s² (t² - 1.2 s * t + 0.36 s²)

38.5 m - 22.6 m/s * t - 4.91 m/s² * t² = -4.91 m/s² * t² + 5.89 m/s * t - 1.77 m

40.3 m - 28.5 m/s * t = 0

t = -40.3 m / -28.5 m/s

t = 1.41 s

The balls are at the same height 1.41 s after the red ball is thrown and 0.81 s after the blue ball is thrown.

The Atwood machine consists of two masses hanging from the ends of a rope that passes over a pulley. Assume that the rope and pulley are massless and that there is no friction in the pulley. If the masses have the values m1=21.1 kg and m2=12.9 kg, find the magnitude of their acceleration ???? and the tension T in the rope. Use ????=9.81 m/s2.

Answers

Answer:

[tex]a=2.36\ m/s^2[/tex]

T=157.06 N

Explanation:

Given that

Mass of first block = 21.1 kg

Mass of second block = 12.9 kg

First mass is heavier than first that is why mass second first will go downward and mass second will go upward.

Given that pulley and string is mass  less that is why both mass will have same acceleration.So lets take their acceleration is 'a'.

So now from force equation

[tex]m_1g-m_2g=(m_1+m_2)a[/tex]

21.1 x 9.81 - 12.9 x 9.81 =(21.1+12.9) a

[tex]a=2.36\ m/s^2[/tex]

Lets tension in string is T

[tex]m_1g-T=m_1a[/tex]

[tex]T=m_1(g-a)[/tex]

T=21.1(9.81-2.36) N

T=157.06 N

The magnitude of their acceleration is 2.36m/s² while the tension in the rope is 157.06N.

From the information given, the following can be depicted:

Mass of first block = 21.1kgMas of second block = 12.9kg

The force equation can be used to calculate the magnitude of the acceleration which will go thus:

(21.1 × 9.81) - (12.9 × 9.81) = (21.1 + 12.9)a

(8.2 × 9.81) = 34a

a = (8.2 × 9.81) / 34

a = 2.36m/s².

Therefore, the tension will be:

T = m(g - a)

T = 21.1(9.81 - 2.36)N

T = 157.06N

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Two resistors have resistances R(smaller) and R(larger), where R(smaller) < R(larger). When the resistors are connected in series to a 12.0-V battery, the current from the battery is 1.12 A. When the resistors are connected in parallel to the battery, the total current from the battery is 9.39 A. Determine the two resistances.

Answers

Final answer:

Using Ohm's law and properties of series and parallel circuits, it's possible to find the resistances. In series, resistances are directly added and for parallel, the reciprocal of total resistance is the sum of reciprocals of individual resistances. Applying these principles with given current and voltage, one can solve for resistances.

Explanation:

This question pertains to electricity and specifically the characteristics of resistors when they are connected in series or parallel. Using Ohm's Law, we know that the voltage (V) is the product of the current (I) and the resistance (R). Therefore, when the resistors are connected in series, the combined resistance (Rtotal) is the sum of the individual resistances, while the current remains the same. This gives us Rtotal = V/I = 12.0V / 1.12A.

When in parallel, however, the total resistance can be found differently. In a parallel circuit, the total resistance is given by 1/Rtotal = 1/R+ 1/R. As per the problem, we know that the total current of the circuit connected in parallel is 9.39 A, so we can use the equation Itotal = V/ Rtotal to find the total resistance in the parallel circuit.

Combining the information from both the circuits would allow us to solve two simultaneous equations to get the values of R and R.

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The two resistances connected in series have a total resistance of 10.71 Ω, and connected in parallel have a total resistance of 1.28 Ω. Solving the equations, we find the resistances to be 1.43 Ω and 9.28 Ω.

Let's solve this step-by-step:

Step 1: Series Connection

When two resistors are connected in series, the total resistance, [tex]R_{total[/tex], is the sum of the resistances:

[tex]R_{total[/tex] = R₁ + R₂

Using Ohm's Law (V = IR), we can find the total resistance in series:

V = 12.0 V;

I = 1.12 A;

[tex]R_{total[/tex] = V/I

[tex]R_{total[/tex] = 12.0 V / 1.12 A = 10.71 Ω

Step 2: Parallel Connection

When the same resistors are connected in parallel, the total resistance, [tex]R_{parallel[/tex], can be found using the formula:

1/[tex]R_{parallel[/tex] = 1/R₁ + 1/R₂

Again, using Ohm's Law, we first find [tex]R_{parallel[/tex]:

V = 12.0 V; [tex]I_{total[/tex] = 9.39 A;

[tex]R_{parallel[/tex] = V/[tex]I_{total[/tex] = 12.0 V / 9.39 A = 1.28 Ω

Step 3: Solving the Equations

We now have two equations:

R₁ + R₂ = 10.71 Ω

(R₁ * R₂) / (R₁ + R₂) = 1.28 Ω (since 1/[tex]R_{parallel[/tex] = 1/R₁ + 1/R₂ )

Let's solve these equations:

Substitute R₂ = 10.71 - R₁ into the parallel equation:

(R₁ * (10.71 - R₁)) / 10.71 = 1.28

R₁ * (10.71 - R₁) = 1.28 * 10.71

10.71R₁ - R₁² = 13.69

R₁² - 10.71R₁ + 13.69 = 0

Solving the quadratic equation using the quadratic formula:

R₁ = [10.71 ± √((10.71)² - 4*1*13.69)] / 2

Solving this, we get R₁ ≈ 1.43 Ω or R₁ ≈ 9.28 Ω

Then, R₂ = 10.71 - 1.43 = 9.28 Ω ,

R₂ = 10.71 - 9.28 = 1.43 Ω

Two train whistles have identical frequencies of 175 Hz. When one train is at rest in the station and the other is moving nearby, a commuter standing on the station platform hears beats with a frequency of 4.05 beats/s when the whistles operate together. What are the two possible speeds and directions the moving train can have? slower speed m/s Correct: Your answer is correct. faster speed m/s Changed: Your submitted answer was incorrect. Your current answer has not been submitted.

Answers

Answer:

The speed of the train is 7.75 m/s towards station.

The speed of the train is 8.12 m/s away from the station.

Explanation:

Given that,

Frequency of the whistles f= 175 Hz

Beat frequency [tex]\Delta f= 4.05 Hz[/tex]

Speed of observer = 0

We need to calculate the frequency

Using formula of beat frequency

[tex]\Delta f=f'-f[/tex]

[tex]f'=\Delta f+f[/tex]

[tex]f'=4.05+175[/tex]

[tex]f'=179.05\ Hz[/tex]

When the train moving towards station, then the frequency heard is more than the actual

Using Doppler effect

[tex]f'=f(\dfrac{v-v_{o}}{v-v_{s}})[/tex]

[tex]v=v-\dfrac{vf}{f'}[/tex]

Put the value into the formula

[tex]v=343-\dfrac{343\times175}{179.05}[/tex]

[tex]v=7.75\ m/s[/tex]

The speed of the train is 7.75 m/s towards station.

When the train moving away form the station

Again beat frequency

[tex]\Delta f=f-f'[/tex]

[tex]f'=f-\Delta [/tex]

[tex]f'=175-4.05[/tex]

[tex]f'=170.95\ Hz[/tex]

We need to calculate the speed

Using Doppler effect

[tex]f'=f(\dfrac{v-v_{o}}{v+v_{s}})[/tex]

[tex]v=\dfrac{vf}{f'}-v[/tex]

Put the value into the formula

[tex]v=\dfrac{343\times175}{170.95}-343[/tex]

[tex]v=8.12\ m/s[/tex]

The speed of the train is 8.12 m/s away from the station.

Hence, This is the required solution.

Consider a river flowing toward a lake at an average velocity of 3 m/s at a rate of 500m3/sat a location 90 m above the lake surface. Determine the total mechanical energy of the river water per unit mass and the power generation potential of the entire river at that location.

Answers

Answer:

mechanical energy per unit mass is 887.4 J/kg

power generated is 443.7 MW

Explanation:

given data

average velocity = 3 m/s

rate = 500 m³/s

height h = 90 m

to find out

total mechanical energy and power generation potential

solution

we know that mechanical energy is sum of potential energy and kinetic energy

so

E = [tex]\frac{1}{2}[/tex]×m×v² + m×g×h    .............1

and energy per mass unit is

E/m =  [tex]\frac{1}{2}[/tex]×v² + g×h

put here value

E/m =  [tex]\frac{1}{2}[/tex]×3² + 9.81×90

E/m = 887.4 J/kg

so mechanical energy per unit mass is 887.4 J/kg

and

power generated is express as

power generated = energy per unit mass ×rate×density

power generated = 887.4× 500× 1000

power generated = 443700000

so power generated is 443.7 MW

Final answer:

The total mechanical energy per unit mass of the river water is the sum of the potential and kinetic energy. The potential energy is calculated using the height and the gravitational constant, while kinetic energy is calculated using velocity. The power generation potential of the river is the total mechanical energy multiplied by the volume flow rate.

Explanation:

The total mechanical energy per unit mass of the river water at this location can be determined using the principle of mechanical energy conservation and the knowledge of potential and kinetic energy. The total mechanical energy (E) equals the potential energy (PE) plus the kinetic energy (KE) per unit mass.

The potential energy is given by: PE = mgh, where m is the mass, g is the acceleration due to gravity (~9.81 m/s^2), and h is the height (90 m above lake surface). But since we are looking for energy per unit mass, m cancels out and we get PE = gh.

The kinetic energy is given by: KE = 0.5mv^2, where v is the velocity (3 m/s). In per unit mass terms, this simplifies to KE = 0.5v^2.

Therefore, E = PE + KE = gh + 0.5v^2.

The power generation potential can be calculated using the equation: P = E * volume flow rate (in our case, 500 m^3/s).

So,​​ P = (gh + 0.5v^2) * 500.

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You go watch your friend as she runs at a cross country meet. The first time she passes you, your friend runs by going due north at a speed of 4.40 m/s. You move to a different place on the course and twelve minutes after you saw her the first time, your friend runs past you again. This time she is traveling at a speed of 3.80 m/s in the direction 30.0° W of S. What is the direction of her average acceleration between those same two times?

Answers

Answer:

76 degree  south of west.

Explanation:

We shall represent velocities in vector form , considering east as  x axes and west as Y axes.

V₁ = 4.4 j

V₂ = 3.8, 30 degree  west of south

V₂ = -  3.8 sin 30 i - 3.8 cos 30 j

= - 1.9 i - 3.29 j

Change in velocity

= V₂ - V₁

= - 1.9 i - 3.29 j - 4.4 j

= - 1.9 i - 7.69 j

Acceleration

= change in velocity / time

(- 1.9 i - 7.69 j  ) / 60 ms⁻² .

Direction of acceleration θ

Tan θ = 7.69 / 1.9 =4.047

θ = 76 degree  south of west.

a speeding car is travelling at a constant 30.0 m/s when it passes a stationary police car. If the police car delays for 1.00 s before starting, what must be the magnitude of the constant acceleration of the police car to catch the speeding car after the police car travels a distance of 300 m?

(A) 6.00 m/s2
(B) 3.00 m/s2
(C) 7.41 m/s2
(D) 1.45 m/s2
(E) 3.70 m/s2

Answers

Answer:

option (C)

Explanation:

Speed of car = 30 m/s

Let the time taken by the police car to catch the speeding car is t

The distance traveled by the speeding car in t + 1 second is equal to the distance traveled by the police car in time t

Distance traveled by the police car in time t

[tex]s=ut + 0.5 at^{2}[/tex]    .... (1)

Distance traveled by the speeding car in t + 1 second

s = 30 (t + 1) = 300

t + 1 = 10

t = 9 s

Put the value of t in equation (1), we get

300 = 0 + 0.5 x a x 9 x 9

a = 7.41 m/s^2

C. 7.41 meters per square second.

In this question, the car is travelling at constant speed, whereas the police car accelerates uniformly after some delay to catch the car, the respective kinematic formulas are shown below:

Car

[tex]x_{C} = x_{o} + v_{C}\cdot t[/tex] (1)

Police car

[tex]x_{P} = x_{o} + \frac{1}{2}\cdot a_{P}\cdot (t-t')^{2}[/tex] (2)

Where:

[tex]x_{o}[/tex] - Initial position, in meters. [tex]x_{C}[/tex] - Final position of the car, in meters.[tex]x_{P}[/tex] - Final position of the car, in meters. [tex]t[/tex] - Time, in seconds.[tex]t'[/tex] - Delay time, in seconds.[tex]a_{P}[/tex] - Acceleration of the police car, in meters per square seconds.[tex]v_{C}[/tex] - Speed of the car, in meters per second.

If we know that [tex]x_{o} = 0\,m[/tex], [tex]x_{C} = x_{P} = 300\,m[/tex], [tex]t' = 1\,s[/tex] and [tex]v_{C} = 30\,\frac{m}{s}[/tex], then we have the following system of equations:

[tex]300 = 30\cdot t[/tex] (1)

[tex]300 = \frac{1}{2}\cdot a_{P}\cdot (t-1)^{2}[/tex] (2)

By (1):

[tex]t = 10[/tex]

Then we find that acceleration of the police car must be:

[tex]300 = \frac{1}{2}\cdot a_{P}\cdot (10-1)^{2}[/tex]

[tex]a_{P} = 7.407\,\frac{m}{s^{2}}[/tex]

Therefore, the correct choice is C.

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The Asian Silver Carp is an invasive species of fish which has infested a number of American rivers. The disturbance of passing boats has been known to make these fish leap large distances out of the water. One such fish leaps with an initial velocity at the water's surface of 11.0 m/s at an angle of 34.0° above the horizontal. How high above the water's surface, in meters, does the fish reach?

Answers

Answer:

1.93 m

Explanation:

Initial velocity of fish u = 11 m /s

Angle of jump = 34 degree.

Vertical component of its velocity = u sin34 = 11 x.5592 = 6.15 m /s

Considering its motion in vertical direction ,

u = 6.15 m/s

g = - 9.8 m /s

maximum height attained = h

From the formula

v² = u² - 2gh

0 = 6.15x 6.15 - 2 x 9.8 h

h = (6.15 x 6.15 )/ 2 x 9.8

= 1.93 m .

Jacob is traveling at 5.00 m/s North. Jacob throws a ball with a velocity of 5.00 m/s South. Jacob throws the ball from a height of 1.45 m above the ground. Assuming gravitational acceleration is 9.81 m/s^2, how long does the ball stay in the air after it is thrown? Describe the motion of the ball relative to the ground. Describe the motion of the ball relative to Jacob.

Answers

Answer:t=0.54 s

Explanation:

Given

Jacob is traveling 5 m/s in North direction

Jacob throw a ball with a in south direction with a velocity of 5 m/s

Ball is thrown in opposite direction of motion of car therefore it seems as if it is dropped from car as its net horizontal velocity is 5-5=0

Time taken by ball to reach ground

[tex]s=ut+\frac{gt^2}{2}[/tex]

[tex]1.45=0+\frac{9.81\times t^2}{2}[/tex]

[tex]t^2=frac{2\times 1.45}{9.81}[/tex]

t=0.54 s

Motion of ball will be straight line

At what distance from a long straight wire carrying a
currentof 5.0A is the magnitude of the magnetic field due to the
wireequal to the strength of the Earth's magnetic field of about
5.0 x10^-5 T?

Answers

Answer:

The distance is 2 cm

Solution:

According to the question:

Magnetic field of Earth, B_{E} = [tex]5.0\times 10^{- 5} T[/tex]

Current, I = 5.0 A

We know that the formula of magnetic field is given by:

[tex]B = \farc{\mu_{o}I}{2\pi d}[/tex]

where

d = distance from current carrying wire

Now,

[tex]d = \frac{\mu_{o}I}{2\pi B}[/tex]

[tex]d = \frac{4\pi\times 10^{- 7}\times 5.0}{2\pi\times 5.0\times 10^{- 5}}[/tex]

d = 0.02 m 2 cm

Final answer:

The distance from the wire where the magnitude of the magnetic field equals the Earth's magnetic field is approximately 0.4 meters.

Explanation:

To find the distance from the wire where the magnitude of the magnetic field is equal to the strength of the Earth's magnetic field, we can use the equation:

B = μ0 * I / (2π * r)

Where B is the magnetic field, μ0 is the permeability of free space (4π x [tex]10^-7[/tex]A), I is the current, and r is the distance from the wire.

Plugging in the given values, we have:


B_wire = μ0 * 5.0A / (2π * r) and B_earth = 5.0 x [tex]10^-5 T[/tex]

Setting B_wire equal to B_earth and solving for r:

5.0 x[tex]10^-5[/tex]* 5.0A / (2π * r)

Solving for r, we find that the distance from the wire where the magnitude of the magnetic field is equal to the Earth's is approximately 0.4 meters.

If a body travels half its total path in the last 1.50 s of its fall from rest, find the total time of its fall (in seconds).

Answers

Answer:

time to fall is 3.914 seconds

Explanation:

given data

half distance time = 1.50 s

to find out

find the total time of its fall

solution

we consider here s is total distance

so equation of motion for distance

s = ut + 0.5 × at²   .........1

here s is distance and u is initial speed that is 0 and a is acceleration due to gravity = 9.8 and t is time

so for last 1.5 sec distance is 0.5 of its distance so equation will be

0.5 s = 0 + 0.5 × (9.8) × ( t - 1.5)²     ........................1

and

velocity will be

v = u + at

so velocity v = 0+ 9.8(t-1.5)    ..................2

so first we find time

0.5 × (9.8) × ( t - 1.5)² = 9.8(t-1.5)  + 0.5 ( 9.8)

solve and we get t

t = 3.37 s

so time to fall is 3.914 seconds

What force will give a 40.0 kg grocery cart an acceleraticn of 2.4 m/s^2?

Answers

Answer:

force is 96 N

Explanation:

given data

mass = 40 kg

acceleration = 2.4 m/s²

to find out

force

solution

we know force is mass time acceleration so

we will apply here force formula that is express as

force = m × a   ..............1

here m is mass and a is acceleration so

put here value in equation 1 we get force

force = 40 × 2.4

force = 96

so force will be 96 N

When the saw slices wood, the wood exerts a 104-N force on the blade, 0.128 m from the blade’s axis of rotation. If that force is at right angles to the lever arm, how much torque does the wood exert on the blade? Does this torque make the blade turn faster or slower?

Answers

Answer:

Explanation:

When saw slices wood by exerting a force on the wood , wood also exerts a reaction force on the saw in opposite direction which is equal to the force of action that is 104 N.

So torque exerted by wood on the blade

= force x perpendicular distance from the axis of rotation

= 104 x .128

=13.312 Nm.

Since this torque opposes the movement of blade , it turns the blade slower.

If a 10kg block is at rest on a table and a 1200N force is applied in the eastward direction for 10 seconds, what is the acceleration on the block? a. How far does the block travel? b. What is the block's final velocity?

Answers

Answer:

120 m/s^2

(a) 6000 m

(b) 1200 m/s

Explanation:

mass, m = 10 kg

initial velocity, u = 0

Force, F = 1200 N

time, t = 10 s

Let a be the acceleration of the block.

By use of Newton,s second law

Force = mass x acceleration

1200 = 10 x a

a = 120 m/s^2

(a) Let the block travels by a distance s.

Use second equation of motion

[tex]s=ut+\frac{1}{2}at^{2}[/tex]

s = 0 + 0.5 x 120  x 10 x 10

s = 6000 m

(b) Let v be the final velocity of the block

Use first equation of motion

v = u + at

v = 0 + 120 x 10

v = 1200 m/s

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