Physics 2070
Exam 2 B:
Blue
Problems.
Show all work, don’t forget units, and circle your answer.
Be neat and organized with your
solutions and explain your reasoning where asked.
1.
(7 points)
A Ford Focus and a Dodge Ram truck are initially at rest on a horizontal parking lot at the
edge of a steep cliff.
For simplicity, we will assume that the Ram has twice as much mass as the
Focus.
Equal constant forces are applied to each car for equal amounts of time as they accelerate
across the surface of the lot (ignore the effects of friction) toward the edge of the cliff.
a.
During the push toward the edge of the cliff, which car has the greater acceleration?
Why?
The Ford has the larger acceleration.
It has a smaller mass and receives the
same force, so it will have a larger acceleration.
b.
Which car has traveled a longer distance toward the cliff when the force is removed?
Why?
The Ford travels a longer distance while the force is being applied.
It has a
smaller mass and larger acceleration, so it will travel a longer distance in the
same amount of time.
c.
Which car is moving faster (has a larger speed) when the force is removed?
Why?
The Ford has a larger speed when the force is removed.
It has a larger
acceleration for a longer time, so it will have a larger speed.
d.
Which car has the larger impulse imparted to it by the applied force? Why?
Both cars will have the same impulse from the applied force.
They have the
same force applied for the same amount of time, so they will have the same
impulse.
e.
Which car has the greater momentum when the force is removed?
Why?
Both cars will have the same momentum.
Impulse is equal to the change in
momentum and since both cars have the same impulse and start from rest, they
will have the same momentum when the force is removed.
f.
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 Spring '08
 THOMPSON
 Force, Kinetic Energy, Mass, Momentum, Work

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