As a train accelerates away from a station, it reaches a speed of 4.6 m/s in 5.2 s. If the train's acceleration remains constant, what is its speed after an additional 7.0 s has elapsed? Express your answer using two significant figures.

Answers

Answer 1

Answer:

Vf = 10.76 m/s

Explanation:

Train kinematics

The train moves with uniformly accelerated movement

[tex]V_f = V_o + a*t[/tex] Formula (1)

Vf: Final speed (m/s)

V₀: Inital speed (m/s)

t: time in seconds (s)

a: acceleration (m/s²)

Movement from t = 0 to t = 5.2s

We replace in formula (1)

4.6 = 0 + a*5.2

a = 4.6/5.2 = 0.88 m/s²

Movement from t = 5.2s to t = 5.2s + 7s = 12.2s

We replace in formula (1)

[tex]V_f = 4.6 + 0.88*7[/tex]

Vf = 10.76 m/s


Related Questions

The output of an ac generator connected to an RLC series combination has a frequency of 12 kHz and an amplitude of 28 V. If R = 4.0 Ohms, L = 30 μH, and C = 800 nF, find a. The impedance b. The amplitude for current c. The phase difference between the current and the emf of the generator

Answers

Answer:

(a) 14.88 ohm

(b) 1.88 A

(c)  -74.4°

Explanation:

Vo = 28 V

f = 12 kHz = 12000 Hz

R = 4 ohm

L = 30 micro henry = 30 x 10^-6 H

C = 800 nF = 800 x 10^-9 F

(a)

The inductive reactance,

XL = 2 π f L = 2 x 3.14 x 12000 x 30 x 10^-6 = 2.26  ohm

The capacitive reactance

[tex]X_{c}=\frac{1}{2\pi fC}=\frac{1}{2 \times 3.14 \times 12000 \times 800 \times 10^{-9}}[/tex]

Xc = 16.59 ohm

Let the impedance is Z.

[tex]Z=\sqrt{4^{2}+\left ( 2.26-16.59 \right )^{2}}[/tex]

Z = 14.88 ohm

(b)

The formula for the amplitude of current

[tex]I_{o}=\frac{V_{o}}{Z}=\frac{28}{14.88}[/tex]

Io = 1.88 A

(c)

Let the phase difference is Ф

[tex]tan\phi =\frac{X_{L}-X_{C}}{R}=\frac{2.26-16.59}{4}=-3.5825[/tex]

Ф = -74.4°

Gamma rays (γ-rays) are high-energy photons. In a certain nuclear reaction, a γ-ray of energy 0.815 MeV (million electronvolts) is produced. Compute the frequency of such a photon. Answer must be in Hz.

Answers

Answer:

Frequency, [tex]\nu=1.96\times 10^{20}\ Hz[/tex]

Explanation:

Given that,

Energy of a gamma rays, [tex]E=0.815\ MeV=0.815\times 10^6\ eV[/tex]

Since, [tex]1\ eV=1.6\times 10^{-19}\ J[/tex]

[tex]0.815\times 10^6\ eV=0.815\times 10^6\times 1.6\times 10^{-19}\ J[/tex]

[tex]E=1.304\times 10^{-13}\ J[/tex]

The energy of a wave is given by :

[tex]E=h\nu[/tex]

[tex]\nu[/tex] is the frequency of such a photon

[tex]\nu=\dfrac{E}{h}[/tex]

[tex]\nu=\dfrac{1.304\times 10^{-13}\ J}{6.63\times 10^{-34}\ Js}[/tex]

[tex]\nu=1.96\times 10^{20}\ Hz[/tex]

So, the frequency of such a photon is [tex]1.96\times 10^{20}\ Hz[/tex]. Hence, this is the required solution.

For which of the following charge distributions would Gauss’s law not be useful for calculating the electric field? A. a uniformly charged sphere of radius R
B. a spherical shell of radius R with charge uniformly distributed over its surface
C. a right circular cylinder of radius R and height h with charge uniformly distributed over its surface
D. an infinitely long circular cylinder of radius R with charge uniformly distributed over its surface
E. Gauss’s law would be useful for finding the electric field in all of these cases.

Answers

Answer:

The correct answer is option 'c'.

Explanation:

Gauss's law theoretically can be used to calculate the electric field by any shape of conductor

According to Gauss's law we have

[tex]\oint _s\overrightarrow{E}\cdot \widehat{ds}=\frac{q_{in}}{\epsilon _o}[/tex]

Now the integral on the right hand side of the above relation is solved easily if there is a high degree of symmetry in the electric field which is  possible in cases when the object is highly symmetric.

The cases of high symmetry include electric fields due to charged spheres, infinite line charge, point charge, infinite plane charged sheet, infinite cylindrical conductor.

But the for the case of limited height of cylinder the symmetry cannot be utilized thus the integral becomes complex to solve, thus cannot be used.  

A 7.00- kg bowling ball moves at 3.00 m/s. How fast musta
2.45- g Ping Pong ball move so that the two balls have the
samekinetic energy?

Answers

Answer:

Ping Pong ball move at velocity 160.4 m/s

Explanation:

given data

mass m1 = 7 kg

velocity v1 = 3 m/s

mas m2 = 2.45 g = 2.45 × [tex]10^{-3}[/tex] kg

same kinetic energy

to find out

How fast Ping Pong ball move (v2)

solution

we know same KE

so

[tex]\frac{1}{2}* m1* v1^{2} = \frac{1}{2}* m2* v2^{2}[/tex]   ...........1

so v2 will be

v2 = [tex]\sqrt{\frac{m1*v1^2}{m2} }[/tex]    .............2

put here value in equation 2 we get v2

v2 = [tex]\sqrt{\frac{7*3^2}{2.45*10^{-3}}}[/tex]

v2 = 160.4

so Ping Pong ball move at velocity 160.4 m/s

Final answer:

Begin with the kinetic energy equation, set the two equal and solve for the unknown velocity of the Ping Pong ball. Substitute the given values into the formula to finalize your answer.

Explanation:

This question involves the concept of kinetic energy, that is equal to 1/2 mass x velocity2 for an object in motion. Let's denote the mass of the bowling ball as m1 (7kg), its velocity as v1 (3m/s), the mass of the Ping Pong ball as m2 (0.00245kg, which is 2.45g in kg), and its velocity as v2, which we need to find. If we assume that the two balls have the same kinetic energy, then:

1/2 * m1 * v12 = 1/2 * m2 * v22

By calculating the left-hand side and then rearranging the equation to solve for v2, we will get the velocity of the Ping Pong ball:

v2 = sqrt((m1 * v12) / m2)

Now substitute the given values into the formula to find the velocity of the Ping Pong ball.

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What is an electric field? (choose all that are true) a) A vector field created by a charged particle.
b) The field created when one charged particle is brought close to another charged particle.
c) A scalar field created by a charged particle.
d) A vector field created only by positive charges.
e) None of the above.

Answers

Answer:

option A

Explanation:

the correct answer is option A

An electric field is a vector field created by charged particle.

Electric field is mathematically defined as the ratio of the vector component of the force to the charge in coulomb.

Si unit of Electric field is N/C

Electric field is created by the electric charge or by the varying magnetic field.

Electric field is responsible for the attractive force between the electron and atomic nucleus.

Displacement vector points due east and has a magnitude of 3.35 km. Displacement vector points due north and has a magnitude of 9.31 km. Displacement vector points due west and has a magnitude of 6.66 km. Displacement vector points due south and has a magnitude of 3.65 km. Find (a) the magnitude of the resultant vector + + + , and (b) its direction as a positive angle relative to due west.

Answers

Answer:

(a) 6.56 km

(b) [tex]59.68^\circ[/tex] north of west

Explanation:

Given:

[tex]\vec{d}_1= 3.35\ km\ east = 3.35\ km\ \hat{i}\\\vec{d}_2= 9.31\ km\ north = 9.31\ km\ \hat{j}\\\vec{d}_3= 6.66\ km\ west = -6.61\ km\ \hat{i}\\\vec{d}_4= 3.65\ km\ south = -3.65\ km\ \hat{j}\\[/tex]

Let the resultant displacement vector be [tex]\vec{D}[/tex].

As the resultant is the vector sum of all the vectors.

[tex]\therefore \vec{D}=\vec{d}_1+\vec{d}_2+\vec{d}_3+\vec{d}_4\\\Rightarrow \vec{D} =(3.35\ km\ \hat{i})+(9.31\ km\ \hat{j})+(-6.61\ km\ \hat{i})+(-3.65\ km\ \hat{j})\\\Rightarrow \vec{D} =-3.31\ km\ \hat{i}+5.66\ km\ \hat{j}\\\textrm{Magnitude of the resultant displacement vector} = \sqrt{(-3.31)^2+(5.66)^2}\ km= 6.56\ km\\[/tex]

[tex]\textrm{Angle with the positive west} = \theta = \tan^{-1}(\dfrac{5.66}{3.31})= 59.68^\circ[/tex]

Final answer:

The magnitude of the resultant vector sum of all the displacements is 6.55 km, and its direction is 59.65° relative to due west.

Explanation:

To find the magnitude of the resultant vector (D = A + B + C + D), we first need to add the displacement vectors head-to-tail. Since each vector points in a cardinal direction, we can add their magnitudes algebraically after designating the direction for each: east and north are positive, while west and south are negative. The resultant in the east-west direction is 3.35 km (east) - 6.66 km (west) = -3.31 km (west). The resultant in the north-south direction is 9.31 km (north) - 3.65 km (south) = 5.66 km (north).

Now we use the Pythagorean theorem to find the magnitude of the resultant:

R = √((-3.31 km)² + (5.66 km)²) = √(10.96 km² + 32.05 km²) = √43.01 km² = 6.55 km

The direction is determined by the tangent of the angle relative to the west. Let φ be the angle, then

tan(φ) = opposite / adjacent = 5.66 km / 3.31 km

φ = arctan(5.66 / 3.31) = 59.65° (north of west)

Therefore, the resultant vector is 6.55 km in magnitude, at an angle of 59.65° relative to due west.

If a force on an object is aimed in the direction of the object’s velocity, the force does: a. no work.
b. positive work.
c. negative work
d. any of the above.

Answers

Answer: If a force on an object is aimed in the direction of the object’s velocity, the force does positive work (b).

Explanation:

Hi, the answer is oprion b. positive work.

If a force on an object is aimed in the direction of the object’s velocity, the force does positive work.

An object's kinetic energy will only change if the force acting on the object changes the object's speed. This will only happen if there is a component of the force in the direction that the object moves.

So, A force will do work only if the force has a component in the direction that the object moves.

 

Final answer:

The answer to the question is 'b. positive work.' If the force on an object is in the direction of the object’s velocity, positive work is done as it adds energy to the system.

Explanation:

If a force on an object is aimed in the direction of the object’s velocity, the force does positive work. Work is defined as the product of the force times the displacement times the cosine of the angle between them.

Since the angle between the force and the displacement is zero when the force is in the direction of velocity (cos 0 = 1), the work done is positive. The work done by a force in the direction of an object's motion adds energy to the system. 

An example of this would be pushing a lawn mower forward, where the force applied and the direction of the mower's motion are the same.

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A 0.50 Kg billard ball moving at 1.5 m/s strikes a second 0.50 kg billiard ball which is at rest on the table.If the first ball slows down to a speed of 0.10 m/s, then what is the speed of the second ball ? Please explain.

Answers

Answer:

velocity of second billiard after collision = 1.4 m/sec  

Explanation:

We have mass of billiard let [tex]m_1=0.5kg[/tex]

Velocity of billiard let [tex]v_1=1.5m/sec[/tex]

Mass of second second billiard let [tex]m_2=0.5kg[/tex]

Velocity of second billiard before collision 0 m/sec  billiard

Velocity of first billiard after collision  0.1 m/sec

Now according conservation of momentum

Momentum before collision and after collision will be same

So momentum before collision = momentum after collision

[tex]0.5\times 1.5+0.5\times 0=0.5\times 0.1+0.5\times velovity\ of\ second\ biliard\ after\ collision[/tex]

So velocity of second billiard after collision = 1.4 m/sec  

Find the work done "by" the electric field on a positively charged point particle with a charge of 2.1x10^-6 C as it is moved from a potential of 15.0 V to one of 8.0 V. (Include the sign of the value in your answer.)

Answers

Answer

Work done will be [tex]14.7\times 10^{-6}J[/tex] and it will be positive

Explanation:

We have given charge [tex]2.1\times 10^{-6}C[/tex]

We have to find work done in moving the charge from 15 volt to 8 volt

Let [tex]V_1=15V\ and\ V_2=8volt[/tex]

So potential difference [tex]V=V_1-V_2=15-8=7volt[/tex]

We know that work done [tex]W=QV[/tex], here Q is charge and V is potential difference

So work done [tex]W=QV=2.1\times 10^{-6}\times 7=14.7\times 10^{-6}J[/tex]

It will be positive work done because work is done in moving charge from higher potential to lower potential  

The electric field due to two point charges is found by: a) finding the stronger field. The net field will just be equal to the strongest field.
b) determining the electric field due to each charge and adding them together as vectors.
c) adding the magnitude of the two fields together.
d) adding the direction of the two fields together.
e) None of the above.

Answers

Answer:

b)determining the electric field due to each charge and adding them together as vectors.

Explanation:

The electric Field is a vector quantity, in other words it has a magnitude and a direction. On the other hand, the electric field follows the law of superposition. The electric field produced by two elements is equal to the sum of the electric fields produced by each element when the other element is not present. in other words, the total electric field is solved determining the electric field due to each charge and adding them together as vectors.

Final answer:

The electric field due to two-point charges is found by determining the electric field of each charge and adding them together as vectors, considering both their magnitudes and directions.

Explanation:

The correct way to find the electric field due to two-point charges is option (b), determining the electric field due to each charge and adding them together as vectors. The electric field is a vector quantity, meaning it has both magnitude and direction. Thus, when two or more electric fields exist in the same region, you add them as vectors, taking into account both their magnitudes and directions. For example, if you have two positive charges, the fields they generate will be in different directions. Therefore, you would add these fields together as vectors, resulting in the net electric field in that region.

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A person is standing on a level floor. His head,upper torso,
arms and hands together weigh 438N and have a centerof gravity that
is 1.17m above the floor. His upper legsweigh 144N and have a
center of gravity that is 0.835m above thefloor. Finally, his lower
legs and feet together weigh 87Nand have a center of gravity that
is 0.270m above the floor. Relative to the floor, find the location
of the center of gravityfor the entire body.

Answers

Answer:

g = 0.98 m

Explanation:

given data:

upper portion weight 438 N and its center of gravity is 1.17 m

upper legs weight 144 N and its center of gravity is 0.835 m

lower leg weight 88 N and its center of gravity is 0.270 m

position of center of gravity of whole body can be determine by using following relation

[tex]g = \frac{\sum ({m_i g_i)}}{\sum m_i}[/tex]

where [tex]m_i[/tex] is mass of respective part and [tex]g_i[/tex] is center of gravity

[tex]g = \frac{\sum{ 438\times 1.17 + 144\times 0.835 + 88\times 0.270}}{438+144+88}[/tex]

g = 0.98 m

When children draw human figures by sketching a circle with dangly lines for legs the children are demonstrating which developmental stage in art?

A. Drawing

B. Schematic

C. pre schematic

D. circular

Answers

Answer:

C

Explanation:

the correct answer is c) Pre Schematic.

It is in the Pre-schematic stage of development that the children learn to draw human figures by sketching a circle with dangly lines for legs. It remains till the age of six. After pre schematic stage comes the schematic stage, where in children can draw complex structures.  

Final answer:

Children drawing human figures with a circle and lines for legs are in the Pre-schematic stage of art development, indicating an early attempt at representational drawing before achieving greater accuracy and detail in later stages.

Explanation:

When children draw human figures by sketching a circle with dangly lines for legs, they are demonstrating the Pre-schematic developmental stage in art. This stage is distinct from the earlier scribbling phase, signaling that children have begun to recognize and attempt to represent the human form in a more organized albeit simplified manner. However, this representation lacks the complexity and accuracy found in later stages, such as the Schematic stage, where more detailed and proportionate figures are drawn.

The Pre-schematic stage typically occurs in children aged between 4 and 7 years old. During this time, their cognitive and motor skills are developing rapidly, but they are still learning how to translate what they see and imagine onto paper with greater fidelity. Thus, the circle and lines approach is a developmentally appropriate method for them to begin exploring human figures in their art.

A cyclotron is designed to accelerate protons (mass 1.67 x 10^-27 kg) up to a kinetic energy of 2.5 x 10^-13 J. If the magnetic field in the cyclotron is 0.75T, what is the radius of the dipole magnets in the cyclotron? 14cm 17cm 24cm 5.8cm

Answers

Answer:

24 cm

Explanation:

Given:

Mass of proton = 1.67 × 10⁻²⁷ Kg

kinetic energy = 2.5 × 10⁻¹³ J

magnetic field in the cyclotron, B = 0.75 T

Now,

Kinetic energy = [tex]\frac{1}{2}mv^2[/tex]  = 2.5 × 10⁻¹³ J

where, v is the velocity of the electron

or

[tex]\frac{1}{2}\times1.67\times10^{-27}\times v^2[/tex]  = 2.5 × 10⁻¹³ J

or

v² = 2.99 × 10¹⁴

or

v = 1.73 × 10⁷ m/s

also,

centripetal force = magnetic force

or

[tex]\frac{mv^2}{r}[/tex]  = qvB

q is the charge of the electron

r is the radius of the dipole magnets

on substituting the respective values, we get

[tex]\frac{1.67\times10^{-27}\times1.73\times10^7}{r}[/tex]  = 1.6 × 10⁻¹⁹ × 0.75

or

r = 0.2408 m ≈ 24 cm

Hence, the correct answer is 24 cm

The radius of the dipole magnets in the cyclotron is mathematically given as

r=24 cm

What is the radius of the dipole magnets in the cyclotron?

Question Parameter(s):

A cyclotron is designed to accelerate protons (mass 1.67 x 10^-27 kg)

Up to kinetic energy of 2.5 x 10^-13 J.

Generally, the equation for the Kinetic energy is mathematically given as

K.E=0.5mv^2  

Therefore

0.5*1.67*10^{-27}*v^2  = 2.5 × 10^{-13} J

v = 1.73 × 10⁷ m/s

In conclusion

mv^2/r  = qvB

(1.67*10^{-27}*1.73*10^7)/r  = 1.6 × 10^{-19}* 0.75

r=24 cm

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Assume that a projectile is fired horizontally from a "gun" located 1 meter above the ground. If the ball strikes the ground a distance of 2 meters from the end of the "gun" determine the muzzle velocity of the gun.

Answers

Answer:

[tex]v_{o}=8.85m/s[/tex]

Explanation:

To determine the muzzle velocity of the gun, we must know how long does it take the ball to strikes the ground

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

Since the ground is at y=0 and [tex]v_{oy}=0[/tex]

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

Solving for t

[tex]t=0.4517s[/tex]

Now, to determine the muzzle velocity we need to find its acceleration first

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

[tex]v=v_{ox}+at[/tex] (2)

If we analyze the final velocity is 0. From (2) we have that

[tex]v_{ox}=-at[/tex] (3)

Replacing (3) in (1)

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

[tex]2=a(0.4517)^{2} (\frac{1}{2}-1)[/tex]

[tex]a=-19.60m/s^{2}[/tex]

Solving (3)

[tex]v_{ox}=-at=-(19.60m/s^{2} )(0.4517s)=8.85m/s[/tex]

What is the the electric field at a point midway between a -7.67 μC and a +5.03 μC charge 3.38 cm apart? Take the direction towards the positive charge to be positive.

Answers

Answer:

-4.01 × 10⁸ N/C.

Explanation:

Given : Charge Q = -7.67 × 10⁻⁶ C

Charge q = + 5.03×10⁻⁶ C

Distance between the charges = 0.0338 m

Let d be the distance from the charge Q and charge q to the mid point.

Midway distance =  d = 0.0169 m

Electric field due to the negative charge = E₁ = k Q / d²

Electric field due to the positive charge = E₂ = k q / d²

Here k = 9 × 10⁹ N m²/C² is the Coulomb's constant.

E₁ = (9 × 10⁹)(7.67 × 10⁻⁶) / (0.0169)² = 2.42 × 10⁸ N/C

E₂ = (9 × 10⁹)( 5.03×10⁻⁶) /(0.0169)² = 1.585 × 10⁸N/C

Assume that the negative charge is  towards the left of the mid point and the positive charge is towards the right of the mid point,

The electric field due to the negative charge is inwards towards the charge(left) and the electric field due to positive charge is outwards and so towards the negative X direction.

Total electric field = E = E₁ + E₂ = -2.42 × 10⁸ - 1.585 × 10⁸

                                                     = - 4.01 × 10⁸ N/C

Direction towards the left (towards the negative charge).

In a remote civilization, distance is measured in urks and an hour is divided into 125 time units named dorts. The length conversion is 1 urk = 58.0 m. Consider a speed of (25.0 + A + B) urks/dort. Convert this speed to meters per second (m/s). Round your final answer to 3 significant figures.Given A=39 and B=18

Answers

Answer:

so speed = 165 m/s

Explanation:

given data

speed = (25.0 + A + B) urks/dort

A = 39

B = 18

1 urk = 58 m

to find out

Convert speed to meters per second

solution

we know speed =  (25.0 + A + B)

put A and B

speed =  (25.0 + 39+ 18) = 82 urk/dort

we know that hour is divided into 125 time units name dorts

so we can say

1 hour = 125 × dorts

and we know 1 hour = 3600 seconds

so

3600 = 125 × dorts

dorts = 28.8 seconds

and we have given

1 urk = 58 m

so 82 urk = 82 × 58 = 4756 m

so from speed

speed = 82 urk/dort

speed =  [tex]82 * \frac{58}{28.8}[/tex] m/s = 165.139

so speed = 165 m/s

Final answer:

The speed (82.0 urks/dort) converts to 165 meters per second when using the given conversion factors, with values A=39 and B=18 included.

Explanation:

To convert a speed from urks/dort to meters per second, we first need to express the speed in urks/dort in terms of meters and seconds, using the given conversions: 1 urk = 58.0 meters and 1 hour = 125 dorts. Given the values A=39 and B=18, the speed in urks/dort is 25.0 + 39 + 18 = 82.0 urks/dort.

Firstly, we convert urks to meters:

(82.0 urks/dort) × (58.0 meters/urk) = 4756 meters/dort

Now, we can convert dorts to seconds. Since 1 hour is divided into 125 dorts and there are 3600 seconds in an hour, there are 3600 seconds / 125 dorts = 28.8 seconds/dort.

Speed in meters per second (m/s) = 4756 meters/dort × (1 dort/28.8 seconds)

Speed in m/s = 165 m/s (rounded to three significant figures)

Therefore, the speed in meters per second is 165 m/s, rounded to three significant figures.

A bullet in a gun is accelerated from the firing chamber to the end of the barrel at an average rate of 5.70 x 10^5 m/s^2 for 9.60 x 10^−4 s. What is its muzzle velocity (in m/s) (that is, its final velocity)? (Enter the magnitude.)

Answers

Final answer:

To calculate the muzzle velocity, we use the equation for constant acceleration (v = u + at) with an initial velocity (u) of 0, the given acceleration (a) of 5.70 x 10^5 m/s^2, and the time (t) of 9.60 x 10^-4 s to find the final velocity (v), which is approximately 547 m/s.

Explanation:

The question concerns calculating the muzzle velocity of a bullet as it's accelerated from the firing chamber to the end of the barrel of a gun.

Using the formula v = u + at, where v is the final velocity, u is the initial velocity (which is zero before the gun is fired), a is the acceleration, and t is the time for which the acceleration is applied, we can find the muzzle velocity. The bullet experiences an acceleration (a) of 5.70 x 105 m/s2 for a time (t) of 9.60 x 10−4 seconds.

Plugging the values into the formula, we get:

v = 0 + (5.70 x 105 m/s2)(9.60 x 10−4 s)

v = 5.47 x 102 m/s

Therefore, the final muzzle velocity of the bullet as it leaves the barrel is approximately 547 m/s.

One common application of conservation of energy in mechanics is to determine the speed of an object. Although the simulation doesn’t give the skater's speed, you can calculate it because the skater's kinetic energy is known at any location on the track. Consider again the case where the skater starts 7 m above the ground and skates down the track. What is the skater's speed when the skater is at the bottom of the track? Express your answer numerically in meters per second to two significant figures.

Answers

Final answer:

The skater's speed at the bottom of the track can be determined using the law of conservation of energy.

Explanation:

The skater's speed at the bottom of the track can be determined by applying the law of conservation of energy. At the top of the track, the skater has only potential energy, which is converted to kinetic energy as the skater moves down the track. The potential energy at the top of the track can be calculated using the equation:

mgh = (1/2)mv2

where m is the mass of the skater, h is the height, and v is the speed of the skater. At the bottom of the track, all the potential energy is converted to kinetic energy, so we can set the potential energy equal to the kinetic energy:

mgh = (1/2)mv2

Rearranging the equation gives:

v = (2gh)

Plugging in the values for mass (which is not given in the question) and height, you can calculate the skater's speed at the bottom of the track.

Aaron was challenged to kick a soccer ball off of the flat roof of the Science Building and into a trashcan 12.3 m away from the edge of the building. The Science Building is 11.3 m tall. Since this is unsafe, Aaron suggested that he works it out on paper instead. Assuming the ball is kicked off the building with only a horizontal velocity, how fast would the ball need to leave the top of the building to land in the trash can?

Answers

Answer:

8.1 m /s

Explanation:

Let the required velocity be v . This is a horizontal velocity so it will cover the horizontal distance of 12.3 m with this velocity without any acceleration .

Time taken t = distance / velocity

t = 12.3 /v

During this period ball also covers vertical distance with initial velocity zero and acceleration of g.

For vertical fall

initial velocity u = 0

Acceleration = g

Time = t

h = ut + 1/2 g t²

11.3 = 0 + .5 x 9.8 x (12.3 / v )²

v² = 65.6

v = 8.1 m /s

An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train. When the engineer first sees the car, the locomotive is 300 m from the crossing and its speed is 18 m/s. If the engineer’s reaction time is 0.45 s, what should be the magnitude of the minimum deceleration to avoid an accident? Answer in units of m/s 2 .

Answers

The magnitude of the minimum deceleration needed to avoid the accident is –0.55 m/s²

To solve the question given above, we'll begin by calculating the distance travelled during the reaction time. This can be obtained as follow:

Speed = 18 m/s

Time = 0.45 s

Distance =?

Speed = distance / time

18 = distance / 0.45

Cross multiply

Distance = 18 × 0.45

Distance = 8.1 m

Thus, the engineer travelled a distance of 8.1 m during the reaction time.

Next, we shall the distance between the engineer and the car. This can be obtained as follow:

Total distance = 300 m

Distance during the reaction time = 8.1 m

Distance between the engineer and the car =?

Distance between the engineer and the car = (Total distance) – (Distance during the reaction time)

= 300 – 8.1

Distance between the engineer and the car = 291.9 m

Finally, we shall determine the magnitude of the deceleration needed to avoid the accident. This can be obtained as follow:

Initial velocity (u) = 18 m/s

Final velocity (v) = 0 m/s

Distance (s) = 291.9 m

Deceleration (a) =?

v² = u² + 2as

0² = 18² + (2 × a × 291.9)

0 = 324 + 583.8a

Collect like terms

0 – 324 = 583.8a

–324 = 583.8a

Divide both side by 583.8

a = –324 / 583.8

a = –0.55 m/s²

Therefore, the magnitude of the deceleration needed to avoid the accident is –0.55 m/s²

Learn more: https://brainly.com/question/2797154

Final answer:

To avoid an accident, the engineer must decelerate the train at a minimum rate of approximately -0.55 m/s^2, taking into account the reaction time which contributed an additional 8.1 m to the stopping distance.

Explanation:

An engineer in a locomotive sees a car stuck on the track and needs to calculate the necessary deceleration to avoid an accident. The engineer has a reaction time of 0.45 seconds, and the initial speed of the train is 18 m/s. The total stopping distance must include the distance traveled during the reaction time plus the actual braking distance.

The distance covered during the engineer's reaction time is found using the formula d = vt, where d is distance, v is velocity, and t is time. We get d = 18 m/s * 0.45 s = 8.1 m.

So, the stopping distance minus the reaction distance is 300 m - 8.1 m = 291.9 m. To find the deceleration, we can use the formula v^2 = u^2 + 2as, where v is the final velocity (which is 0), u is the initial velocity, a is the acceleration (deceleration in this case), and s is the distance. Solving for a, we get a = -u^2 / (2s). Substituting the values, a = -(18 m/s)^2 / (2 * 291.9 m), resulting in a deceleration of approximately -0.55 m/s^2.

Discuss whether the kinetic energy or the momentum of the ""bullet"" is more important in causing damage to the bulletproof vest.

Answers

Answer:

Answered

Explanation:

The Kinetic energy of a bullet does not remain constant. It dissipates as the bullet travel through the air. It is partly converted into heat, sound, air resistance etc.

Whereas the momentum of a travelling body remains conserved and hence constant. therefore a bullet with more momentum will cause more damage. that is momentum is more important than kinetic energy.

How much work do you do when you lift a 15-kg box to a height of 5.0 m? 75 J
735 J
980 J
735 lb
147 N

Answers

Answer:

735 J

Explanation:

mass of box, m = 15 kg

Height, h = 5 m

Work is defined as the product of force and the displacement in the  direction of force.

W = F x S

Work is a scalar quantity and its SI unit is Joule.

Here, Force, F = m x g = 15 x 9.8 = 147 N

So, W = 147 x 5 = 735 J

Thus, the work is 735 J.

Represent 0.783 kg with Sl units having an appropriate prefix Express your answer to three significant figures and include the appropriate units. P: A Value RO ? Units 0.783 kg

Answers

Answer:

783 grams

Explanation:

Here a time of 0.783 kg is given.

Some of the prefixes of the SI units are

1 gram = 10⁻³ kilogram

1 milligram = 10⁻⁶ kilogram

1 microgram = 10⁻⁹ kilogram

The number is 0.783

Here, the only solution where the number of significant figures is three is gram

[tex]1\ kilogram = 1000\ gram[/tex]

[tex]\\\Rightarrow 0.783\ kilogram=0.783\times 1000\ gram\\ =783\ gram[/tex]

So, 0.783 kg = 783 grams

Four point charges are located at the corners of a square. Each charge has magnitude 4.50 nC and the square has sides of length 2.80 cm. Find the magnitude of the electric field (in N/C) at the center of the square if all of the charges are positive and three of the charges are positive and one is negative.

Answers

Final answer:

The magnitude of the electric field at the center of a square with four point charges (either all positive or three positive and one negative) each of magnitude 4.50 nC and sides of length 2.80 cm, is zero. This outcome is due to symmetry and the principle of superposition.

Explanation:

To find the magnitude of the electric field at the center of a square due to point charges located at its corners, we use the principle of superposition. This entails calculating the electric field contribution from each charge individually and then vectorially adding these contributions together.

For our case, where all charges have a magnitude of 4.50 nC and the square has sides of length 2.80 cm, the geometry of the problem simplifies the calculations significantly.

When all four charges are positive, they all contribute to the electric field in a symmetrically outward manner relative to the center. Thus, their contributions in terms of magnitude cancel out, making the net electric field at the center zero.

In the scenario where three charges are positive and one is negative, we approach the problem similarly. However, the negative charge introduces an incongruence in the symmetry. Its electric field contribution will 'attract' rather than 'repel' like the other three positive charges.

Despite this, due to the square's symmetry and equal magnitude of the charges, the net electric field at the center still cancels out, resulting in zero magnitude.

This conclusion is based on symmetry and the principle that equal point charges at equal distances in a square configuration result in a net zero electric field at the square's center, irrespective of the sign when the magnitudes are equal.

A runner slows down from a 9.50 m/s at a rate of 2.30 m/s^2 . (a) How far does she travel in the next 6.00 s? (b) What is her final velocity? (c) Evaluate the result. Does it make sense?

Answers

Answer:

(a) d = 15.6 m

(b) v' = - 4.3 m/s

Given:

Initial velocity, v = 9.50 m/s

Acceleration, a = [tex] - 2.30 m/s^{2][/tex] or deceleration = 2.30[tex]m/s^{2}[/tex]

Solution:

(a) For the calculation of the distance covered, we use eqn (2) of motion:

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

where

d = distance covered in time t

t = 6 s (Given)

Now,

[tex]d = 9.50\times 6 - \frac{1}{2}\times 2.30times 6^{2}[/tex]

d = 15.6 m

(b) For the calculation of her final velocity, we use eqn 1 of motion:

v' = v + at

v' = 9.50 + (- 2.30)(6) = - 4.3 m/s

(c) Since, the final velocity after the body slows down comes out to be negative and the distance covered and displacement of the body are different, it does not make sense.

How many protons are required to generate a charge of +25.0 C?

Answers

Answer:

[tex]N=1.56*10^{20}[/tex] protons

Explanation:

The total charge Q+=+25.0C is the sum of the charge of the N protons, with charge q :

[tex]Q_{+}=N*q_{p}[/tex]

q_{p}=1.6*10^{-19}C    charge of a proton

We solve to find N:

[tex]N=Q_{+}/q_{p}=25/(1.6*10^{-19})=1.56*10^{20}[/tex]

Find the frequency (in hertz) of the first overtone for a 1.75 m pipe that is closed at only one end. Use 350 m/s for the speed of sound in air. Also, would increasing the air temperature raise, lower, or have no effect upon this frequency?

Answers

Answer:

The first overtone frequency is 100 Hz.

Solution:

According to the question:

Length of pipe, l = 1.75 m

Speed of sound in air, v_{sa} = 350 m/s

Frequency of first overtone, [tex]f_{1}[/tex] is given by:

[tex]f_{1} = \frac{v_{sa}}{2l}[/tex]

[tex]f_{1} = \frac{350}{2\times 1.75} = 100 Hz[/tex]

Since, the frequency, as clear from the formula depends only on the speed

and the length. It is independent of the air temperature.

Thus there will be no effect of air temperature on the frequency.

You toss a ball straight up at 6.8 m/s ; it leaves your hand at 2.0 m above the floor. Suppose you had tossed a second ball straight down at 6.8 m/s (from the same place 2.0 m above the floor). When would the second ball hit the floor?

Answers

Answer:0.249 s

Explanation:

Given

Ball is tossed down with a velocity of 6.8 m/s downward

height from ground=2 m

therefore time to reach ground is

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

[tex]2=6.8\times t+\frac{9.81\times t^2}{2}[/tex]

[tex]9.81t^2+13.6t-4=0[/tex]

[tex]t=\frac{-13.6\pm \sqrt{13.6^2+4\times 4\times 9.81}}{2\times 9.81}[/tex]

[tex]t=\frac{-13.6+18.49}{19.62}=0.249 s[/tex]

Assuming that the limits of the visible spectrum are approximately 380 and 700 nm, find the angular range of the first-order visible spectrum produced by a plane grating that has 900 grooves/mm with the light incident normally on the grating.

Answers

Answer:

angular range is ( 0.681 rad , 0.35 rad )

Explanation:

given data

wavelength λ = 380 nm = 380 × [tex]10^{-9}[/tex] m

wavelength λ  = 700 nm =  700 × [tex]10^{-9}[/tex] m

to find out

angular range of the first-order

solution

we will apply here slit experiment equation that is

d sinθ = m λ    ...........1

here m is 1 for single slit and d is = [tex]\frac{1}{900*10^3 m}[/tex]

so put here value in equation 1 for 380 nm

we get

d sinθ = m λ

[tex]\frac{1}{900*10^3}[/tex] sinθ = 1 × 380 × [tex]10^{-9}[/tex]

θ = 0.35 rad

and for 700 nm

we get

d sinθ = m λ

[tex]\frac{1}{900*10^3}[/tex] sinθ = 1 × 700 × [tex]10^{-9}[/tex]

θ = 0.681 rad

so angular range is ( 0.681 rad , 0.35 rad )

Does orbital direction of a planet affect its synodic period as seen from earth?

Answers

Answer:

Yes

Explanation:

Yes, the orbital direction of a planet affect its Synodic period as seen from earth. The synodic period of mercury is about 116 days on Earth. Whereas the sidereal period of mercury as seen from Earth is 88 days.  This difference is caused by the simultaneous motion of Earth in its orbit. Hence we can say that the  orbital direction of a planet affect its synodic period as seen from earth.

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