Name: ________________________ Class: ___________________ Date: __________
Quiz 3--PHYS 201-1M--Chapters 5 & 6
Multiple Choice (3 pts each)
Identify the choice that best completes the statement or answers the question. Use g=10m/s2 for each problem.
1. A box is being pulled across a rough floor at a constant speed. What can you say about the work done by
friction?
a. friction does no work
c. friction does negative work
b. friction does positive work
d. friction does both positive and negative
work.
2. How does the work required to stretch a spring 6 cm compare with the work required to stretch it 2 cm?
a. 2 times as much work to stretch it 6 cm
d. 9 times as much work to stretch it 6 cm
b. 3 times as much work to stretch it 6 cm
e. 12 times as much work to stretch it 6 cm
c. 4 times as much work to stretch it 6 cm
3. A 1.0 kg block is travelling to the right at 3.0 m/s. It collides with a stationary 2.0 kg block, and the two blocks
stick together. What is their final velocity?
a. 1 m/s
c. 3 m/s
b. 2 m/s
d. 1.5 m/s
4. Which of these statements is true?
a. energy is a scalar quantity;
c. both energy and momentum are vector
momentum is a vector
quantities
b. both energy and momentum are scalar
d. energy is a vector;
quantities
momentum is scalar
5. Two boxes, one heavier than the other, are initially at rest on a horizontal frictionless surface. The same constant
force F acts on each one for exactly 1 second. Which box has more momentum after the force acts?
a. the heavy one
c. both the same
b. the light one
1
Name: ________________________
6. A 75-kg swimmer dives horizontally off a 500-kg raft. If the diver's speed immediately after leaving the raft is 4
m/s, what is the corresponding raft speed?
a. 0.2 m/s
b. 0.5 m/s
c. 0.6 m/s
d. 4.0 m/s
7. In which of these collisions is momentum conserved?
a. people colliding
c. cars colliding
b. gas particles colliding
d. all of these
8. An elastic collision is one in which
a. only momentum is conserved
c. both energy and momentum are
conserved
b. only energy is conserved
d. neither energy or momentum are
conserved
2
Name: ________________________
Problem
9. (25 pts) Consider this inclined plane. The 10kg block is initially at rest.
Part I
Consider the plane to be frictionless.
a) What is the speed at point (a), which is halfway down?
b)What is the speed at the bottom [point (b)]?
Part II
Now consider there to be a force along the plane that is described by this function:
F(x)  2x
a) If the block travels along the entire length of the plane, how much work is done by the force?
b) What is the speed at the bottom of the plane?
3
Name: ________________________
10. (15 pts) Consider this perfectly inelastic collision. What is the final velocity of the 2 particles?
4
Name: ________________________
11. (20 pts) An object is initially at rest and has mass=2 kg. The object is acted on by a force
displacement

d  4i  2j m.
a) How much work is done on the object by the force?
b) What is the object’s speed at
  4i  2j m?
d
c) Is the x-component of the force doing positive or negative work on the object?
d) Is the y-component of the force doing positive or negative work on the object?
.
5
  2i  3j N
F
over a
Name: ________________________
12. (15 pts) Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 7.5 m/s, and
just after is 2.5 m/s. If the ball is in contact with the floor for 0.01 s, what is the magnitude of the average force
applied by the floor on the ball?
.
6
ID: A
Quiz 3--PHYS 201-1M--Chapters 5 & 6
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
C
D
A
A
C
C
D
C
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
DIF: 2
TOP: 6.2 Conservation of Momentum
PROBLEM
9. ANS:
.
PTS: 1
10. ANS:
.
PTS: 1
11. ANS:
.
PTS: 1
12. ANS:
.
PTS: 1
1