Physics 2A Sample Exam Questions
Exam 1 Sample Questions
Exam 2 Sample Questions
Exam 3 Sample Questions
Exam 4 Sample Questions
Physics 2A Exam 1 Sample Questions
1. A truck starts from rest and rolls down a hill with
constant acceleration. It travels a distance of 400 m in the first 20
s.
a. Find the acceleration of the truck.
b. Find the velocity of the truck after 20 s.
2. A Russian balloonist is ascending at a constant
rate of 4 m/s. When he is at an altitude of 250 m, he accidentally drops
his samovar. How high will he be above the ground when the samovar hits
the ground?
3. A ball is thrown horizontally from the roof of a
building 60 ft high at a velocity of 100 ft/s.
a. How long will it take for the ball to hit the ground?
b. What is the magnitude and direction of the ball's velocity the instant
before it hits the ground?
4. Give a careful definition of
a. velocity
b. acceleration
5. A pilot heads his airplane due east at a speed of
75 m/s. While he is flying, a wind blows at 60 degrees North of East with
a constant speed of 25 m/s.
a. What is the resultant velocity of the plane? (Make a rough sketch,
but calculate your answer mathematically.)
b. How long will it take the plane to travel 100 km?
6. A car slows from a speed of 30 m/s to 20 m/s while
travelling a distance of 125 m.
a. What constant acceleration must the car have?
b. How long does it take for the car to travel the 125 m mentioned in
part a?
7. A truck starts from rest and rolls down a hill with
constant acceleration. It travels a distance of 400 m in the first 20
s.
a. Find the acceleration of the truck.
b. Find the velocity of the truck after 20 s.
8. A rocket, initially at rest, climbs vertically upward
with an acceleration of 6 m/s^2 for 10 s.
a. How fast is the rocket going after the 10 s?
b. What maximum height does the rocket reach?
9. Given two vectors: A with magnitude of 20 at 25
degrees and B with magnitude of 10 at 70 degrees (angles are with respect
to the positive x-axis)
a. Make a sketch showing the addition of A and B.
b. Find A + B (magnitude and direction) by the component method.
10. A car is travelling at a velocity of 15 m/s when
it starts to slow down at a rate of -1.5 m/s^2. If the car slows down
at this rate for 6 s,
a. how fast will the car be going?
b. If the car continues to slow down at this rate, how far will it travel
before coming to a stop?
11. A golf ball is thrown with a velocity of 25 m/s
at an angle of 400 degrees above the horizontal. Find the maximum height
of the golf ball.
12. Given the following two vectors:
A has a length of 10 m and points at 20 degrees above the positive x axis.
B has a length of 20 m and points at 40 degrees below the positive x axis.
a. Make a rough sketch of the vector A + B.
b. Calculate the vector A + B by using components.
13. A car slows from a speed of 30 m/s to 20 m/s while
travelling a distance of 125 m.
a. What constant acceleration must the car have?
b. How long does it take for the car to travel the 125 m mentioned in
part a?
14. A ball thrown vertically upward reaches the top
of its path at t = 1.5 s.
a. What will be the height of the ball in meters at t = 2.5 s?
b. What is the acceleration of the ball at the very top of its path?
15. A frustrated physics student throws his text horizontally
from the top of a 40 m high building with a velocity of 5 m/s. How far
away from the building is the book when it hits the ground?
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1. A 7 kg box slides down a ramp inclined at 40° with
the horizontal. The coefficient of kinetic friction between the ramp and
the box is 0.35.
a. Make a careful free-body diagram of the box.
b. Find the acceleration of the box.
2. A 1200 kg car is traveling along a level road at
15 m/s when the driver sees a cow standing in the road. The driver panics
and slams on the brakes skidding to a stop in a distance of 30 m. Find
the force of friction acting on the car while it was slowing down.
3. State Newton's three laws of motion. Give an example
for each to show that you understand the concept.
4. A 3 kg mass is to be accelerated up a frictionless
30° incline by a horizontal force as shown. Find the magnitude of the
force, P, needed to cause an acceleration of 2.5 m/s2.
5. A person pushes a 3 kg box across a floor at a speed
of 2 m/s. The box is released and slides a distance of 5 m before coming
to a stop. Find the friction force acting on the box.
6. A 12 kg mass is pushed across a horizontal surface
by a force of 80 N inclined at an angle of 30° with the horizontal as
shown. The coefficient of sliding friction is 0.35.
a. Make a free body diagram of the mass and find the normal force acting
on the mass.
b. Find the force of friction acting on the mass.
c. Find the acceleration of the mass as it moves across the surface.
7. A 3 kg object sitting at the top of the track shown
is given an initial velocity of 4 m/s. Assuming that the track is perfectly
frictionless,
a. Calculate the total energy of the object at the start (point A).
b. Find the velocity of the object at point B.
8. Molly (50 kg) and Jeff (75 kg) are skating on frictionless
rollerskates. While Molly is standing motionless, Jeff crashes into her
and hangs on. Their speed immediately after the collision is 2 m/s. How
fast was Jeff travelling before the collision?
9. A 2000 kg car is travelling north at 15 m/s when
it overtakes and crashes into a 5000 kg truck, also travelling north and
moving with a speed of 10 m/s. a. Find the velocity of the combined wreckage
the instant after the collision. b. What percentage of the kinetic energy
is lost in the collision?
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Physics 2A Exam 3 Sample Questions
1. Starting with Newton's 2nd Law, use the Law of Gravitation
to show that the velocity of a satellite following a circular orbit around
the earth is given by
v2 = GMe/r
2. The velocity of a certain satellite in a circular
orbit about the earth is 4.5 km/s. What would the velocity of this satellite
be if the radius of the orbit were increased by 35 percent?
3. Two students stand at each end of a 100 N horizontal
beam and support its weight. The beam is 4 m long. In addition a 50 N
box sits on the beam 1.5 m from one end. Find the upward force that each
student exerts on the beam.
4. A phonograph record starts from rest and reaches
a final rotational speed of 78 rev/min in a time of 3.5 s.
a. What is the angular acceleration fo the record?
b. How many revolutions does the record make during the 3.5 s?
c. How far does a 10 g bug travel in the first 2 s if it sits a a point
7.0 cm from the center of the record?
5. A car travels around a level, circular curve of
radius 200 m. If the coefficient of static friction between the road and
the car is 0.43, what is the maximum speed that the car can have to safely
negoitate the curve?
6. A 20 kg door is opened by by pushing on the outside
edge (the edge furthest from the hinges)of the door with a force of 20
N that acts at right angles to the door. The width of the door is 90 cm.
How long does it take to rotate the door through a 90o angle?
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Physics 2A Exam 4 Sample Questions
1. A certain heat engine operates over the cycle shown
in the PV diagram. a. Find the net work done by the engine in one cycle.
b. If the heat input
per cycle to the engine is 400 kJ, find the heat exhausted each cycle
(using the results from part a).
c. What is the efficiency
of the engine?
2. The rms velocity of a certain type of molecule in
a room is determined to be 500 m/s when the temperature is 25o
C. What would the temperaure have to be if the rms velocity of the molecules
were to double?
3. An object radiates energy at a temperature of 400
K. What would the temperature of the object need to be if it is to radiate
energy at twice the original rate? An inventor claims to have invented
a heat engine that takes in 1200 J of energy and exhausts 400 J during
each cycle. The engine operates between 600 K and 300 K. Would you invest
money in this engine? Explain.
4. Find the equilibrium temperature when a 500 9 chunk
of iron at 600°C is dropped into 1.5 kg of water at 0°C.
5. A 10 liter tank is to be filled with oxygen at 20oC
at a pressure of 50 atm. Using the ideal gas law, find the mass of oxygen
needed.
6. A ferry boat is 5 m wide and 7 m long. When a large
truck pulls onto the boat it sinks 5 cm lower in the water. What is the
weight of the truck? Explain your work.
a. The top of a cubical box with 2 m long sides is submerged 3 m under
water. Find the force exerted on the top of the box by the pressure
of the water.
b. Find the force exerted on the bottom of the box due to the presssure
of the water.
c. Give a statement of Archimedes principle.
d. Find the buoyant force on the box using Archimedes principle and
show that it is equal to the difference between the two forces found
in parts b and c.
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