PHYS 141 Exam 2 Concept EXAM QUESTIONS AND
CORRECT VERIFIED ANSWERS LATEST UPDATE
2026/2027 (GRADED A+)
A tractor driving at a constant speed pulls a sled loaded with firewood.
There is friction between the sled and the road. The total work done on
the sled after it has moved a distance d is - VERIFIED ANSWER - Zero.
Assuming a circular orbit, the work done by the gravitational force
exerted on the Earth by the Sun during a short time interval in which the
Earth moves through a displacement in its orbital path is - VERIFIED
ANSWER - Zero.
Two iceboats (one of mass m, one of mass 2m) hold a race on a
frictionless, horizontal, frozen lake. Both iceboats start at rest, and the
wind exerts the same constant force on both iceboats. Which iceboat
crosses the finish line with more kinetic energy (KE)? - VERIFIED ANSWER
- They both cross the finish line with the same kinetic energy, but the
iceboat with mass m crosses with more speed.
A block of mass m is placed at rest on a frictionless incline of angle theta.
It is released and slides a distance s along the incline before reaching the
,floor. The floor exerts a kinetic friction force f on the block. After
reaching the floor the block slides a distance x (different from s) and
stops. The net work done on the block during its entire motion is -
VERIFIED ANSWER - zero.
A piece of fruit falls straight down. As it falls, the - VERIFIED ANSWER -
gravitational force does positive work on it and the gravitational PE
decreases.
You throw a ball straight up into the air. At the same time, your friend
drops an identical ball from the same height above the ground at which
you throw yours. Ignoring air resistance, throughout the motion of both
balls, the change in kinetic energy of your ball is - VERIFIED ANSWER - the
same as that of your friends.
You are testing a new car using crash test dummies. Consider two ways
to slow the car from 90 km/h (56 mi/h) to a complete stop:
(i) You let the car slam into a wall, bringing it to a sudden stop.
(ii) You let the car plow into a giant tub of gelatin so that it comes to a
gradual halt.
In which case is there a greater impulse of the net force on the car? -
VERIFIED ANSWER - The impulse is the same in both cases.
, Object 1 and Object 2 have equal kinetic energies. How do the magnitudes
of their momenta, p1 and p2, compare? - VERIFIED ANSWER - Not enough
information to decide.
The mass of the moon is 1/81 of the mass of the earth. Compared to the
gravitational force that the earth exerts on the moon, the gravitational
force that the moon exerts on the earth is - VERIFIED ANSWER - equally
strong.
Compared to the earth, a distant planet has twice the mass and twice the
radius. This means that compared to the earth's surface gravity, the
surface gravity on the other planet is - VERIFIED ANSWER - half as much.
A box is sitting in the back of the truck. The truck begins to accelerate
forward (to the right) and the box does not slip. In a free-body diagram
for the box, the force of friction on the box points - VERIFIED ANSWER - to
the right.
A cable attached to a car holds the car at rest on the frictionless ramp.
The ramp exerts a normal force on the car. How does the magnitude Fn of
CORRECT VERIFIED ANSWERS LATEST UPDATE
2026/2027 (GRADED A+)
A tractor driving at a constant speed pulls a sled loaded with firewood.
There is friction between the sled and the road. The total work done on
the sled after it has moved a distance d is - VERIFIED ANSWER - Zero.
Assuming a circular orbit, the work done by the gravitational force
exerted on the Earth by the Sun during a short time interval in which the
Earth moves through a displacement in its orbital path is - VERIFIED
ANSWER - Zero.
Two iceboats (one of mass m, one of mass 2m) hold a race on a
frictionless, horizontal, frozen lake. Both iceboats start at rest, and the
wind exerts the same constant force on both iceboats. Which iceboat
crosses the finish line with more kinetic energy (KE)? - VERIFIED ANSWER
- They both cross the finish line with the same kinetic energy, but the
iceboat with mass m crosses with more speed.
A block of mass m is placed at rest on a frictionless incline of angle theta.
It is released and slides a distance s along the incline before reaching the
,floor. The floor exerts a kinetic friction force f on the block. After
reaching the floor the block slides a distance x (different from s) and
stops. The net work done on the block during its entire motion is -
VERIFIED ANSWER - zero.
A piece of fruit falls straight down. As it falls, the - VERIFIED ANSWER -
gravitational force does positive work on it and the gravitational PE
decreases.
You throw a ball straight up into the air. At the same time, your friend
drops an identical ball from the same height above the ground at which
you throw yours. Ignoring air resistance, throughout the motion of both
balls, the change in kinetic energy of your ball is - VERIFIED ANSWER - the
same as that of your friends.
You are testing a new car using crash test dummies. Consider two ways
to slow the car from 90 km/h (56 mi/h) to a complete stop:
(i) You let the car slam into a wall, bringing it to a sudden stop.
(ii) You let the car plow into a giant tub of gelatin so that it comes to a
gradual halt.
In which case is there a greater impulse of the net force on the car? -
VERIFIED ANSWER - The impulse is the same in both cases.
, Object 1 and Object 2 have equal kinetic energies. How do the magnitudes
of their momenta, p1 and p2, compare? - VERIFIED ANSWER - Not enough
information to decide.
The mass of the moon is 1/81 of the mass of the earth. Compared to the
gravitational force that the earth exerts on the moon, the gravitational
force that the moon exerts on the earth is - VERIFIED ANSWER - equally
strong.
Compared to the earth, a distant planet has twice the mass and twice the
radius. This means that compared to the earth's surface gravity, the
surface gravity on the other planet is - VERIFIED ANSWER - half as much.
A box is sitting in the back of the truck. The truck begins to accelerate
forward (to the right) and the box does not slip. In a free-body diagram
for the box, the force of friction on the box points - VERIFIED ANSWER - to
the right.
A cable attached to a car holds the car at rest on the frictionless ramp.
The ramp exerts a normal force on the car. How does the magnitude Fn of
