Answer:
d=9.462×10^15 meters
Explanation:
Relation between distance, temps and velocity:
d=v*t
t=1year*(365days/1year)*/(24hours/1day)*(3600s/1h)=31536000s
So:
1 light year=d=3*10^8m/s*3.154*10^7s=9.462×10^15 meters
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.
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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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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It’s the 18th century and you are responsible for artillery. Victory hangs in the balance and it all depends on you making a good shot towards the enemy fortress. Thankfully, your physics class gave you all the tools to calculate projectile trajectories. Your cannon launches a cannonball at an initial speed of 100 m/s and you set the angle at 53 degrees from the horizontal. Calculate (a) how far from the fortress should you position your cannon in order to hit it at its foundation?; and (b) how far from the fortress should you position your cannon in order to hit it at its top height (10 m) in order to knock it down? (g = 9.8 m/s^2)
Answer:
a) You should position the cannon at 981 m from the wall.
b) You could position the cannon either at 975 m or 7.8 m (not recomended).
Explanation:
Please see the attached figure for a graphical description of the problem.
In a parabolic motion, the position of the flying object is given by the vector position:
r =( x0 + v0 t cos α ; y0 + v0 t sin α + 1/2 g t²)
where:
r = position vector
x0 = initial horizontal position
v0 = module of the initial velocity vector
α = angle of lanching
y0 = initial vertical position
t = time
g = gravity acceleration (-9.8 m/s²)
The vector "r" can be expressed as a sum of vectors:
r = rx + ry
where
rx = ( x0 + v0 t cos α ; 0)
ry = (0 ; y0 + v0 t sin α + 1/2 g t²)
rx and ry are the x-component and the y-component of "r" respectively (see figure).
a) We have to find the module of r1 in the figure. Note that the y-component of r1 is null.
r1 = ( x0 + v0 t cos α ; y0 + v0 t sin α + 1/2 g t²)
Knowing the the y-component is 0, we can obtain the time of flight of the cannon ball.
0 = y0 + v0 t sin α + 1/2 g t²
If the origin of the reference system is located where the cannon is, the y0 and x0 = 0.
0 = v0 t sin α + 1/2 g t²
0 = t (v0 sin α + 1/2 g t) (we discard the solution t = 0)
0 = v0 sin α + 1/2 g t
t = -2v0 sin α / g
t = -2 * 100 m/s * sin 53° / (-9.8 m/s²) = 16.3 s
Now, we can obtain the x-component of r1 and its module will be the distance from the wall at which the cannon sould be placed:
x = x0 + v0 t cos α
x = 0 m + 100m/s * 16.3 s * cos 53
x = 981 m
The vector r1 can be written as:
r1 = (981 m ; 0)
The module of r1 will be: [tex]x = \sqrt{(981 m)^{2} + (0 m)^{2}}[/tex]
Then, the cannon should be placed 981 m from the wall.
b) The procedure is the same as in point a) only that now the y-component of the vector r2 ( see figure) is not null:
r2y = (0 ; y0 + v0 t sin α + 1/2 g t² )
The module of this vector is 10 m, then, we can obtain the time and with that time we can calculate at which distance the cannon should be placed as in point a).
module of r2y = 10 m
10 m = v0 t sin α + 1/2 g t²
0 = 1/2 g t² + v0 t sin α - 10 m
Let´s replace with the data:
0 = 1/2 (-9.8 m/s² ) t² + 100 m/s * sin 53 * t - 10 m
0= -4.9 m/s² * t² + 79.9 m/s * t - 10 m
Solving the quadratic equation we obtain two values of "t"
t = 0.13 s and t = 16.2 s
Now, we can calculate the module of the vector r2x at each time:
r2x = ( x0 + v0 t cos α ; 0)
r2x = (0 m + 100m/s * 16.2 s * cos 53 ; 0)
r2x = (975 m; 0)
Module of r2x = 975 m
at t = 0.13 s
r2x = ( 0 m + 100m/s * 0.13 s * cos 53 ; 0)
r2x = (7.8 m ; 0)
module r2x = 7.8 m
You can place the cannon either at 975 m or at 7.8 m (see the red trajectory in the figure) although it could be dangerous to place it too close to the enemy fortress!
A 50 cm^3 block of iron is removed from an 800 degrees Celsius furnance and immediately dropped into 200 mL of 20 degrees Celsius water. What percentage of the water boils away?
Answer:
% of water boils away= 12.64 %
Explanation:
given,
volume of block = 50 cm³ removed from temperature of furnace = 800°C
mass of water = 200 mL = 200 g
temperature of water = 20° C
the density of iron = 7.874 g/cm³ ,
so the mass of iron(m₁) = density × volume = 7.874 × 50 g = 393.7 g
the specific heat of iron C₁ = 0.450 J/g⁰C
the specific heat of water Cw= 4.18 J/g⁰C
latent heat of vaporization of water is L_v = 2260 k J/kg = 2260 J/g
loss of heat from iron is equal to the gain of heat for the water
[tex]m_1\times C_1\times \Delta T = M\times C_w\times \Delta T + m_2\times L_v[/tex]
[tex]393.7\times 0.45\times (800-100) = 200\times 4.18\times(100-20) + m_2\times 2260[/tex]
m₂ = 25.28 g
25.28 water will be vaporized
% of water boils away =[tex]\dfrac{25.28}{200}\times 100[/tex]
% of water boils away= 12.64 %
The percentage of the water boils away when the iron block is placed into the water after furnace is 1264%.
What is heat transfer?The heat transfer is the transfer of thermal energy due to the temperature difference.The heat flows from the higher temperature to the lower temperature.
The heat transfer of a closed system is the addition of change in internal energy and the total amount of work done by it.
As the initial volume of the iron block is 50 cm³ and the density of the iron is 7.874 g/cm³. Thus the mass of the iron block is,
[tex]m=50\times7.874\\m=393.7\rm g[/tex]
The temperature of the furnace is 800 degrees Celsius and the specific heat of the iron block is 0.45 J/g-C.
As the boiling point of the water is 100 degree Celsius. Thus the heat loss by the block of iron is,
[tex]Q_L=393.7\times0.45\times(800-100)\\Q_L=124015.5[/tex]
The latent heat of the water is 2260 J/g. Thus the heat gain by vaporized water is,
[tex]Q_v=2260\times m_v\\[/tex]
Now the heat gain by the water is equal to the heat loss by the iron block.
As the specific heat of the water is 4.18 J/g-C and the temperature of the water is 20 degrees and volume of water is 200 ml.
Thus heat gain by water can be given as,
[tex]Q_G=Q_L=200\times4.18(100-20)+2260m_v\\124015.5=200\times4.18(100-20)+2260m_w\\m_v=25.28\rm g[/tex]
Thus the total amount of the water boils away is 25.28 grams.
The percentage of the water boils away is,
[tex]p=\dfrac{25.25}{200}\times100\\p=12.64[/tex]
Thus the percentage of the water boils away when the iron block is placed into the water after furnace is 1264%.
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A mountain climber stands at the top of a 47.0-m cliff that overhangs a calm pool of water. She throws two stones vertically downward 1.00 s apart and observes that they cause a single splash. The first stone had an initial velocity of −1.40 m/s. (Indicate the direction with the sign of your answers.) (a) How long after release of the first stone did the two stones hit the water? (Round your answer to at least two decimal places.)
Answer:
t = 2.96 s
Explanation:
Since the two stones hit the water at same instant of time
so we will have
[tex]d =vt + \frac{1}{2}gt^2[/tex]
here we know that
d = 47 m
v = 1.4 m/s
[tex]g = 9.81 m/s^2[/tex]
[tex]d = 1.40 t + \frac{1}{2}(9.81) t^2[/tex]
now by solving above equation for d = 47 m
t = 2.96 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
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 body-centered cubic lattice has a lattice constant of 4.83 Ă. A plane cutting the lattice has intercepts of 9.66 Å, 19.32 Å, and 14.49 Å along the three cartesian coordi- nates. What are the Miller indices of the plane?
Along the three Cartesian coordinates. The Miller indices of the plane are [tex](1/2,1/4,1/3)[/tex].
A system known as Miller indices is used to explain how crystal planes and directions inside a crystalline substance are oriented. They serve as a tool to depict the crystal lattice's three-dimensional configuration of atoms or lattice points. In order to describe the surfaces and axes of crystals, Miller indices are frequently used in crystallography.
Miller indices are a crucial tool that crystallographers use to convey crystallographic data and comprehend the geometric arrangement of atoms in crystals. They support the characterization of crystal structures, the prediction of material characteristics, and the comprehension of the microscopic behavior of materials.
Given:
Intercepts = [tex]9.66\ A, 19.32\ A, 14.49\ A[/tex]
Lattice constant, [tex]a = 4.83\ A[/tex]
The reciprocal of intercepts is given as:
[tex]r = (1/9.66),1/19.32,1/14.49)[/tex]
The Miller indices are given as:
[tex]M = r/(1/a)\\M = ((1/9.66),1/19.32,1/14.49))/(1/4.83)\\M = (1/2,1/4,1/3)[/tex]
Hence, along the three Cartesian coordinates. The Miller indices of the plane are [tex](1/2,1/4,1/3)[/tex].
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The Miller indices for a plane intercepting a body-centered cubic lattice with intercepts of 9.66 Å, 19.32 Å, and 14.49 Å are (6,3,4). These are found by taking reciprocals of the intercepts, then multiplying by a common factor to get the smallest set of integers.
Explanation:The student's question is about finding the Miller indices of a plane in a body-centered cubic lattice with given lattice constants and plane intercepts. Miller indices describe the orientation of a plane or set of planes in a crystal lattice.
To find these, we first take the reciprocals of the intercepts, which in this case gives us 1/2, 1/4, and 1/3. We then need to multiply these by a common factor to eliminate any fractions and get the smallest set of integers. Multiplying by 12 gives us the Miller indices of (6,3,4).
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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.
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
A paratrooper is initially falling downward at a speed of 27.6 m/s before her parachute opens. When it opens, she experiences an upward instantaneous acceleration of 74 m/s^2. (a) If this acceleration remained constant, how much time would be required to reduce the paratrooper's speed to a safe 4.95 m/s? (Actually the acceleration is not constant in this case, but the equations of constant acceleration provide an easy estimate.) (b) How far does the paratrooper fall during this time interval?
Answer:
a) 0.31 s
b) 19.77 m
Explanation:
We will need the following two formulas:
[tex]V_{f} = V_{0}+at\\\\X=V_{0}t + \frac{at^{2}}{2}[/tex]
We first use the final velocity formula to find the time that it takes to decelerate the paratrooper:
[tex]4.95\frac{m}{s}=27.6\frac{m}{s}-74\frac{m}{s^{2}}t\\\\-22.65\frac{m}{s}=-74\frac{m}{s^{2}}t\\\\t= \frac{22.65\frac{m}{s}}{74\frac{m}{s^{2}}}=0.31s[/tex]
Now that we have the time, we can use the distance formula to calculate the distance travelled by the paratrooper:
[tex]X=27.6\frac{m}{s}*0.31s - \frac{74\frac{m}{s^{2}}*(0.31 s)^{2}}{2}=19.77 m[/tex]
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).
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
Gas mileage actually varies slightly with the driving speed of a car (as well as with highway vs. city driving). Suppose your car averages 35 miles per gallon on the highway if your average speed is 45 miles per hour, and it averages 19 miles per gallon on the highway if your average speed is 72 miles per hour. Answer parts (a) and (b) below..
(a) What is the driving time for a 2600-mile trip if you drive at an average speed of 45 miles per hour? What is the driving time at 72 miles per hour?
(b) Assume a gasoline price of $3.05 per gallon. What is the gasoline cost for a 2600-mile trip if you drive at an average speed of 45 miles per hour? What is the gasoline cost at 72 miles per hour?
Answer:
a) Traveling at 45 mph, the driving time is 58 h. Traveling at 72 mph, the driving time will be 36 h.
b) Traveling at 45 mph, the gasoline cost will be $225.7.
Traveling at 72 mpg, the gasoline cost will be $417.9
Explanation:
The average speed can be calculated as the distance traveled over time:
speed = distance / time
Then:
time = distance / speed
a)If you drive at an average speed of 45 mph during a 2600-mile trip, the driving time will be:
time = 2600 mi / 45 mi/h = 58 h
If you drive at 72 mph:
time = 2600 mi / 72 mi/h = 36 h
b) For the 2600-mile trip, you will need ( 2600 mi * (1 gallon/ 35 mi)) 74 gallons if you travel at 45 mph.
If you travel at 72 mph, you will need (2600 mi * (1 gallon /19 mi)) 137 gallons.
Traveling at 45 mph, the gasoline cost will be (74 gallons * ($3,05/gallon)) $225.7
Traveling at 72 mph, the gasoline cost will be (137 gallons * (3.05/gallon)) $417.9
A hollow sphere of inner radius 8.82 cm and outer radius 9.91 cm floats half-submerged in a liquid of density 948.00 kg/m^3. (a) What is the mass of the sphere? (b) Calculate the density of the material of which the sphere is made.
Answer:
a) 0.568 kg
b) 474 kg/m³
Explanation:
Given:
Inner radius = 8.82 cm = 0.0882 m
Outer radius = 9.91 cm = 0.0991 m
Density of the liquid = 948.00 Kg/m³
a) The volume of the sphere = [tex]\frac{4\pi}{3}\times(0.0991^2-0.0882^2)[/tex]
or
volume of sphere = 0.0012 m³
also, volume of half sphere = [tex]\frac{\textup{Total volume}}{\textup{2}}[/tex]
or
volume of half sphere = [tex]\frac{\textup{0.0012}}{\textup{2}}[/tex]
or
Volume of half sphere =0.0006 m³
Now, from the Archimedes principle
Mass of the sphere = Weight of the volume of object submerged
or
Mass of the sphere = 0.0006× 948.00 = 0.568 kg
b) Now, density = [tex]\frac{\textup{Mass}}{\textup{Volume}}[/tex]
or
Density = [tex]\frac{\textup{0.568}}{\textup{0.0012}}[/tex]
or
Density = 474 kg/m³
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.
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
Suppose 30.4 mol of krypton is in a rigid box of volume 46 cm3 and is initially at temperature 438.28°C. The gas then undergoes isobaric heating to a temperature of 824°C. (a) What is the final volume of the gas? (b) It is then isothermally compressed to a volume 24.3cm3; what is its final pressure? cm (a) Answer part (a) Answer part (b) (b) Pa
Answer:
Explanation:
Initial volume v₁ =46 x 10⁻⁶ m³
Initial temperature T₁ = 438.28 + 273 = 711.28 K
Initial pressure P₁ = nRT₁ / v₁
= 30.4 x8.3 x 711.28 / (46 x 10⁻⁶ )
= 3901.5 x 10⁶ Pa
Final temperature T₂ = 824 + 273 = 1097 K
Final volume V₂ =?
For isobaric process
v₁ / T₁ = V₂ / T₂
V₂ = V₁ X T₂ /T₁
= 46 X 10⁻⁶ X 1097/ 711.28
= 70.94 X 10⁻⁶ m³ = 70.94 cm³
b ) For isothermal change
P₁ V₁ = P₂V₂
P₂ = P₁V₁ / V₂
= 3901.5 X 10⁶ X 46 / 24.3
7385.55 X 10⁶ Pa.
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 ?
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.
A 7450 kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.35 m/s2 and feels no appreciable air resistance. When it has reached a height of 520 m , its engines suddenly fail so that the only force acting on it is now gravity.
(a) What is the maximum height this rocket will reach above the launch pad?
(b) How much time after engine failure will elapse before the rocket comes crashing down to the launch pad?
(c) How fast will it be moving just before it crashes?
Answer:
a) 520m
b) 10.30 s
c) 100,95 m/s
Explanation:
a) According the given information, the rocket suddenly stops when it reach the height of 520m, because the engines fail, and then it begins the free fall.
This means the maximum height this rocket reached before falling was 520 m.
b) As we are dealing with constant acceleration (due gravity) [tex]g=9.8 \frac{m}{s^{2}}[/tex] we can use the following formula:
[tex]y=y_{o}+V_{o} t-\frac{gt^{2}}{2}[/tex] (1)
Where:
[tex]y_{o}=520 m[/tex] is the initial height of the rocket (at the exact moment in which it stops due engines fail)
[tex]y=0[/tex] is the final height of the rocket (when it finally hits the launch pad)
[tex]V_{o}=0[/tex] is the initial velocity of the rocket (at the exact moment in which it stops the velocity is zero and then it begins to fall)
[tex]g=9.8m/s^{2}[/tex] is the acceleration due gravity
[tex]t[/tex] is the time it takes to the rocket to hit the launch pad
Clearing [tex]t[/tex]:
[tex]0=520 m+0-\frac{9.8m/s^{2} t^{2}}{2}[/tex] (2)
[tex]t^{2}=\frac{-520 m}{-4.9 m/s^{2}}[/tex] (3)
[tex]t=\sqrt{106.12 s^{2}[/tex] (4)
[tex]t=10.30 s[/tex] (5) This is the time
c) Now we need to find the final velocity [tex]V_{f}[/tex] for this rocket, and the following equation will be perfect to find it:
[tex]V_{f}=V_{o}-gt[/tex] (6)
[tex]V_{f}=0-(9.8 m/s^{2})(10.30 s)[/tex] (7)
[tex]V_{f}=-100.95 m/s[/tex] (8) This is the final velocity of the rocket. Note the negative sign indicates its direction is downwards (to the launch pad)
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?
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
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?
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
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.
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 = 12.9kgThe 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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A driver has a reaction time of 0.50 s , and the maximum deceleration of her car is 6.0 m/s^2 . She is driving at 20 m/s when suddenly she sees an obstacle in the road 50 m in front of her. What is the distance she passes after noticing the obstacle before fully stopping? Express your answer with the appropriate units.
Answer:
The car stops after 32.58 m.
Explanation:
t = Time taken for the car to stop
u = Initial velocity = 20 m/s
v = Final velocity = 0
s = Displacement
a = Acceleration = -6 m/s²
Time taken by the car to stop
[tex]v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-20}{-6}\\\Rightarrow t=3.33\ s[/tex]
Total Time taken by the car to stop is 0.5+3.33 = 3.83 s
[tex]s=ut+\frac{1}{2}at^2\\\Rightarrow s=20\times 3.83+\frac{1}{2}\times -6\times 3.83^2\\\Rightarrow s=32.58\ m[/tex]
The car stops after 32.58 m.
Distance between car and obstacle is 50-32.58 = 17.42 m
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
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 baseball is thrown down a hill. This baseball has on-board sensors that can measure its velocities in both the x- and y- directions. The data show that the ball took off with an initial velocity in the y-direction of +4.0 m/s and had a final velocity of –5.8 m/s. Calculate the hang time of the ball. [HINT: Believe it or not, it is possible to calculate hang time (the total time the projectile is in the air) by knowing only the initial and final velocities in the y-direction.]
Answer:1 s
Explanation:
Given
Initial velocity in Y-direction [tex]v_1[/tex]=+4 m/s
Final Velocity in Y-direction [tex]v_2=-5.8 m/s[/tex]
Acceleration in Y-direction is 9.81 [tex]m/s^2[/tex]
Using equation of motion
v=u+at
[tex]-5.8=4+9.81\times t[/tex]
[tex]t=0.998 \approx 1 s[/tex]
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.
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]
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?
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.
If the car’s speed decreases at a constant rate from 71 mi/h to 50 mi/h in 3.0 s, what is the magnitude of its acceleration, assuming that it continues to move in a straight line? What distance does the car travel during the braking period?
Answer:
The acceleration and the distance are 25200 mi/h² and 0.1008 mi.
Explanation:
Given that,
Initial speed = 71 mi/h
Final speed = 50 mi/h
Time = 3.0 s
(a). We need to calculate the acceleration
Using equation of motion
[tex]v=u+at[/tex]
[tex]a=\dfrac{v-u}{t}[/tex]
Put the value in the equation
[tex]a=\dfrac{(50-71)\times3600}{3}[/tex]
[tex]a=-25200\ mi/h^2[/tex]
Negative sign shows the deceleration.
(b). We need to calculate the distance
Using equation of motion
[tex]v^2=u^2+2as[/tex]
[tex](50)^2=(71)^2+2\times(-25200)\times s[/tex]
[tex]s=\dfrac{(50)^2-(71)^2}{-25200}[/tex]
[tex]s=0.1008\ mi[/tex]
Hence, The acceleration and the distance are 25200 mi/h² and 0.1008 mi.
The distance traveled by the car when the car is constantly deaccelerating at a rate of 25200 miles/h² is 0.0504 miles.
Given to us
Initial Velocity of the car, u = 71 miles/h
Final Velocity of the car, v = 50 miles/h
Time = 3.0 s [tex]=\dfrac{3}{3600}[/tex] hour
What is the acceleration of the car?According to the first equation of motion, acceleration can be written as,
[tex]a=\dfrac{v-u}{t}[/tex]
substituting the values we get,
[tex]a=\dfrac{50-71}{\dfrac{3}{3600}}[/tex]
[tex]a=-25,200\rm\ miles/h^2[/tex]
Thus, the acceleration of the car is -25,200 miles/h².
What distance does the car travel during the braking period?According to the third equation of motion,
[tex]v^2-u^2=2as[/tex]
Substituting the values we get,
[tex](50)^2-(71)^2=2(-25200)s[/tex]
[tex]s = 0.0504 \rm\ miles[/tex]
Thus, the distance car travel during the braking period is 0.0504 miles.
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The position of a ship traveling due east along a straight line is s(t) = 12t2 + 6. In this example, time t is measured in hours and position s is measured in nautical miles. We will take s = 0 to be the port of Wilmington, NC and the positive direction to be east. How far east of Wilmington is the ship and how fast is it going after one hour, that is, when t = 1?
Answer:
18 miles east; 24 mph east
Explanation:
In order to find how far east of Wilmington is the ship after 1 hour, we just need to substitute t = 1 into the formula of the position.
The equation of the position is
[tex]s(t) = 12 t^2 +6[/tex]
where t is the time. Substituting t = 1,
[tex]s(1) = 12 (1)^2 + 6 = 12+6 = 18 mi[/tex]
So, the ship is 18 miles east of Wilmington.
To find the velocity of the boat, we just need to calculate the derivative of the position, so
[tex]v(t) = s'(t) = 24 t[/tex]
And by substituting t = 1, we find the velocity after 1 hour:
[tex]v(1) = 24 (1) = 24 mph[/tex]
And the direction is east.
A place-kicker must kick a football from a point 36.0 m (about 40 yards) from the goal. Half the crowd hopes the ball will clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 23.6 m/s at an angle of 45.0° to the horizontal. (a) By how much does the ball clear or fall short (vertically) of clearing the crossbar? (Enter a negative answer if it falls short.)
_______m
(b) Does the ball approach the crossbar (and cross above or beneath it) while still rising or while falling?
rising or falling? _________
Answer:
Part (a) 10.15 m
Part (b) Rising
Explanation:
Given,
Initial speed of the ball = u = 23.6 m/sHeight of the crossbar = h = 3.05 mDistance between the ball and the cross bar = r = 36.0 mAngle of projection = [tex]\theta\ =\ 45.0^o[/tex]Initial velocity of the ball in the horizontal direction = [tex]u_x\ =\ ucos\theta[/tex]Initial velocity of the ball in the vertical direction = [tex]u_y\ =\ usin\theta[/tex]part (a)
Let 't' be the time taken to reach the ball to the cross bar,
In x-direction,
[tex]\therefore r\ =\ u_xt\\\Rightarrow t\ =\ \dfrac{r}{u_x}\ =\ \dfrac{r}{ucos\theta}\\\Rightarrow t\ =\ \dfrac{36.0}{23.6cos45^o}\\\Rightarrow t\ =\ 2.15\ sec[/tex]
Let y be the height attained by the ball at time t = 2.15 sec,
[tex]y\ =\ u_yt\ \ -\ \dfrac{1}{2}gt^2\\\Rightarrow y\ =\ usin\theta t\ -\ \dfrac{1}{2}gt^2\\\Rightarrow y\ =\ 23.6\times sin45^o\times 2.15\ -\ 0.5\times 9.81\ 2.15^2\\\Rightarrow y\ =\ 13.205\ m[/tex]
Now Let H be the height by which the ball is clear the crossbar.
[tex]\therefore H\ =\ y\ -\ h\ =\ 13.205\ -\ 3.05\ =\ 10.15\ m[/tex]
part (b)
At the maximum height the vertical velocity of the ball becomes zero.
i,e, [tex]v_y\ =\ 0[/tex]
Let h be the maximum height attained by the ball.
[tex]\therefore v_y^2\ =\ u_y^2\ -\ 2gh\\\Rightarrow 0\ =\ (usin\theta)^2\ -\ 2gh\\\Rightarrow h\ =\ \dfrac{(usin\theta)^2}{2g}\\\Rightarrow h\ =\ \dfrac{23.6\times sin45.0^o)^2}{2\times 9.81}\\\Rightarrow h\ =\ 14.19\ m[/tex]
Hence at the cross bar the ball attains the height 13.205 m but the maximum height is 14.19 m. Therefore the ball is rising when it reaches at the crossbar.
A car starts from rest and accelerates at a constant rate until it reaches 70 mi/hr in a distance of 220 ft, at which time the clutch is disengaged. The car then slows down to a velocity of 40 mi/hr in an additional distance of 480 ft with a deceleration which is proportional to its velocity. Find the time t for the car to travel the 700 ft.
Answer:
[tex]T = 10.43 s[/tex]
Explanation:
During deceleration we know that the deceleration is proportional to the velocity
so we have
[tex]a = - kv[/tex]
here we know that
[tex]\frac{dv}{dt} = - kv[/tex]
so we have
[tex]\frac{dv}{v} = -k dt[/tex]
now integrate both sides
[tex]\int \frac{dv}{v} = -\int kdt[/tex]
[tex]ln(\frac{v}{v_o}) = - kt[/tex]
[tex]ln(\frac{40}{70}) = - k(t)[/tex]
[tex]kt = 0.56[/tex]
Also we know that
[tex]a = \frac{vdv}{ds}[/tex]
[tex]-kv = \frac{vdv}{ds}[/tex]
[tex]\int dv = -\int kds[/tex]
[tex](v - v_o) = -ks[/tex]
[tex](40 - 70)mph = - k (480 ft)[/tex]
[tex]-30 mph = -k(0.091 miles)[/tex]
[tex]k = 329.67[/tex]
so from above equation
[tex]t = \frac{0.56}{329.67} = 1.7 \times 10^{-3} h[/tex]
[tex]t = 6.11 s[/tex]
initially it starts from rest and uniformly accelerate to maximum speed of 70 mph and covers a distance of 220 ft
so we have
d = 220 ft = 67 m = 0.042 miles[/tex]
now we know that
[tex]d = \frac{v_f + v_i}{2} t[/tex]
[tex]0.042 = \frac{70 + 0}{2} t[/tex]
[tex]t = 4.32 s[/tex]
so total time of motion is given as
[tex]T = 4.32 + 6.11 = 10.43 s[/tex]
An airplane flies horizontally with a constant speed of 172.0 m/s at an altitude of 1390 m. A package is dropped out of the airplane. Ignore air resistance. The magnitude of the gravitational acceleration is 9.8 m/s2. Choose the RIGHT as positive x-direction. Choose UPWARD as positive y-direction Keep 2 decimal places in all answers
(a) What is the vertical component of the velocity (in m/s) just before the package hits the ground? Pay attention to the direction (the sign).
(b) What is the magnitude of the velocity (in m/s) (including both the horizontal and vertical components) of the package just before it hits the ground?
Answer:
(a) - 165.032 m/s
(b) 238.37 m/s
Explanation:
initial horizontal velocity, ux = 172 m/s
height, h = 1390 m
g = 9.8 m/s^2
Let it strikes the ground after time t.
Use second equation of motion in vertical direction
[tex]s=ut+\frac{1}{2}at^{2}[/tex]
-1390 = 0 - 0.5 x 9.8 x t^2
t = 16.84 second
(a) Let vy be the vertical component of velocity as it strikes the ground
Use first equation of motion in vertical direction
vy = uy - gt
vy = 0 - 9.8 x 16.84
vy = - 165.032 m/s
Thus, the vertical component of velocity as it strikes the ground is 165.032 m/s downward direction.
(b)
The horizontal component of velocity remains constant throughout the motion.
vx = 172 m/s
vy = - 165.032 m/s
The resultant velocity is v.
[tex]v=\sqrt{172^{2}+165.032^{2}}[/tex]
v = 238.37 m/s
Thus, teh velocity with which it hits the ground is 238.37 m/s.
Initially, a 2.00-kg mass is whirling at the end of a string (in a circular path of radius 0.750 m) on a horizontal frictionless surface with a tangential speed of 5 m/s. The string has been slowly winding around a vertical rod, and a few seconds later the length of the string has shortened to 0.250 m. What is the instantaneous speed of the mass at the moment the string reaches a length of 0.250 m?
Answer:
[tex] v_f = 15 \frac{m}{s} [/tex]
Explanation:
We can solve this problem using conservation of angular momentum.
The angular momentum [tex]\vec{L}[/tex] is
[tex]\vec{L} = \vec{r} \times \vec{p}[/tex]
where [tex]\vec{r}[/tex] is the position and [tex]\vec{p}[/tex] the linear momentum.
We also know that the torque is
[tex]\vec{\tau} = \frac{d\vec{L}}{dt} = \frac{d}{dt} ( \vec{r} \times \vec{p} )[/tex]
[tex]\vec{\tau} = \frac{d}{dt} \vec{r} \times \vec{p} + \vec{r} \times \frac{d}{dt} \vec{p} [/tex]
[tex]\vec{\tau} = \vec{v} \times \vec{p} + \vec{r} \times \vec{F} [/tex]
but, as the linear momentum is [tex]\vec{p} = m \vec{v}[/tex] this means that is parallel to the velocity, and the first term must equal zero
[tex]\vec{v} \times \vec{p}=0[/tex]
so
[tex]\vec{\tau} = \vec{r} \times \vec{F} [/tex]
But, as the only horizontal force is the tension of the string, the force must be parallel to the vector position measured from the vertical rod, so
[tex]\vec{\tau}_{rod} = 0 [/tex]
this means, for the angular momentum measure from the rod:
[tex]\frac{d\vec{L}_{rod}}{dt} = 0 [/tex]
that means :
[tex]\vec{L}_{rod} = constant[/tex]
So, the magnitude of initial angular momentum is :
[tex]| \vec{L}_{rod_i} | = |\vec{r}_i||\vec{p}_i| cos(\theta)[/tex]
but the angle is 90°, so:
[tex]| \vec{L}_{rod_i} | = |\vec{r}_i||\vec{p}_i| [/tex]
[tex]| \vec{L}_{rod_i} | = r_i * m * v_i[/tex]
We know that the distance to the rod is 0.750 m, the mass 2.00 kg and the speed 5 m/s, so:
[tex]| \vec{L}_{rod_i} | = 0.750 \ m \ 2.00 \ kg \ 5 \ \frac{m}{s} [/tex]
[tex]| \vec{L}_{rod_i} | = 7.5 \frac{kg m^2}{s} [/tex]
For our final angular momentum we have:
[tex]| \vec{L}_{rod_f} | = r_f * m * v_f[/tex]
and the radius is 0.250 m and the mass is 2.00 kg
[tex]| \vec{L}_{rod_f} | = 0.250 m * 2.00 kg * v_f [/tex]
but, as the angular momentum is constant, this must be equal to the initial angular momentum
[tex] 7.5 \frac{kg m^2}{s} = 0.250 m * 2.00 kg * v_f [/tex]
[tex] v_f = \frac{7.5 \frac{kg m^2}{s}}{ 0.250 m * 2.00 kg} [/tex]
[tex] v_f = 15 \frac{m}{s} [/tex]
Answer:
15 m/s
Explanation:
L = mvr
Li = (2.00 kg)(0.750 m)(5m/s) = 7.5 kgm^2/s
conservation of angular momentum --> Li=Lf
Lf = 7.5 kgm^2/s
7.5 kgm^2/s = (2.00 kg)(0.250 m)(vf)
vf = 15 m/s
Raindrops acquire an electric charge as they fall. Suppose a 2.4-mm-diameter drop has a charge of +13 pC. In a thunderstorm, the electric field under a cloud can reach 15,000 N/C, directed upward. For a droplet exposed to this field, how do the magnitude of the electric force compare to those of the weight force and what is the dircetion of the electric force?
Answer:
567.126 x 10⁻⁶ N
[tex]5.6 x 10^{-6} N[/tex]
Explanation:
Thinking process:
[tex]13pC = 13 x 10^{-12} C[/tex]
The electric field is given by E = 15000 N/C
Electric force on the charge
= charge x electric field
= 13 x 10⁻¹² x 15000
= 195 x 10⁻⁹ N.
The force acts in upward direction as force on positive charge acts in the direction in which electric field exists.
Volume of droplet = 4/3 π R³
R = 2.4 X 10⁻³ m
Volume V = 4/3 x 3.14 x ( 2.4 x 10⁻³)³
= 57.87 x 10⁻⁹ m³
density of water = 1000 kg / m³
mass of water droplet = density x volume
= 1000 x 57. 87 x 10⁻⁹ kg
= 57.87 x 10⁻⁶ kg .
Weight = mass x g
= 57.87 x 10⁻⁶ x 9.8
= 567.126 x 10⁻⁶ N.
Therefore, the weight is more than the electric force.