Transcript Ch 6 Pretest

Pre-AP Physics
Ch 6
Momentum
Pretest
1. Which of the following is
an example of a visible
change in momentum?
A) A car runs into a brick wall.
B) A fly hits the windshield of a car.
C) An outfielder catches a baseball.
1. Which of the following is
an example of a visible
change in momentum?
A) A car runs into a brick wall.
B) A fly hits the windshield of a car.
C) An outfielder catches a baseball.
2. A roller coaster climbs up a hill at
4 m/s and then zips down the hill at
30.0 m/s. The momentum of the roller
coaster:
a. is greater up the hill than down the
hill
b. is greater down the hill than up the
hill
c. remains the same throughout the ride
d. is zero throughout the ride
2. A roller coaster climbs up a hill at
4 m/s and then zips down the hill at
30.0 m/s. The momentum of the roller
coaster:
a. is greater up the hill than down the
hill
b. is greater down the hill than up the
hill
c. remains the same throughout the ride
d. is zero throughout the ride
3. An ice skater initially skating at a
velocity of 3 m/s speeds up to a
velocity of 5 m/s. The momentum
of the skater:
a. decreases
b. increases
c. remains the same
d. becomes zero
3. An ice skater initially skating at a
velocity of 3 m/s speeds up to a
velocity of 5 m/s. The momentum
of the skater:
a. decreases
b. increases
c. remains the same
d. becomes zero
4. The change in an object’s
momentum is equal to:
a. the product of the mass of the
object and the time interval.
b. the product of the force applied to
the object and the time interval.
c. the time interval divided by the net
external force.
d. the net external force divided by the
time interval.
4. The change in an object’s
momentum is equal to:
a. the product of the mass of the
object and the time interval.
b. the product of the force applied to
the object and the time interval.
c. the time interval divided by the net
external force.
d. the net external force divided by the
time interval.
5. A softball with a mass of 0.11 kg
moves at a speed of 12 m/s. Then
the ball is hit by a bat and rebounds
in the opposite direction at a speed
of 15 m/s. What is the change in
momentum of the ball?
a. -1.3 kg•m/s
b. -1.6 kg•m/s
c. -0.33 kg•m/s
d. -3.0 kg•m/s
5. A softball with a mass of 0.11 kg
moves at a speed of 12 m/s. Then
the ball is hit by a bat and rebounds
in the opposite direction at a speed
of 15 m/s. What is the change in
momentum of the ball?
a. -1.3 kg•m/s
b. -1.6 kg•m/s
c. -0.33 kg•m/s d. -3.0 kg•m/s
6. Which of the following statements about the
conservation of momentum is NOT correct?
a. Momentum is conserved for a system of
objects pushing away from each other.
b. Momentum is not conserved for a system of
objects in a head-on collision.
c. Momentum is conserved when two or more
interacting objects push away from each other.
d. The total momentum of a system of
interacting objects remains constant regardless
of forces between the objects.
6. Which of the following statements about the
conservation of momentum is NOT correct?
a. Momentum is conserved for a system of
objects pushing away from each other.
b. Momentum is not conserved for a system of
objects in a head-on collision.
c. Momentum is conserved when two or more
interacting objects push away from each other.
d. The total momentum of a system of
interacting objects remains constant regardless
of forces between the objects.
1. What does it
mean to say that
momentum is
conserved?
The total momentum
of a system does not
change unless acted
upon by an
unbalanced force.
2. A rubber ball with a mass of
0.10 kg moves at 20 m/s. It hits
a brick wall and rebounds at a
speed of 15 m/s in the opposite
direction. What is the change in
momentum of the ball?
p = mv
p = 0.10 kg x (20 m/s + 15 m/s)
p = 3.5 kgm/s
3. How is the
momentum of a
running child affected
when he runs into a
stone wall and stops?
The child’s
momentum
decreases to zero.
4. How are
impulse and
momentum
related?
Impulse is equal
to the change in
momentum.
Ft = Dmv
5. A 40.0 kg boy and a
30.0 kg girl are each floating
on inflatable swimming pool
mats. The girl pushes the
boy, who moves away at a
speed of 3.0 m/s. What is
the girl's speed?
Dmv = Dmv
40 kg x 3 m/s = 30 kg x v
120 kgm/s = 30 kg x v
v = 4 m/s