Download Wksht Momentum and Collisions

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Momentum, Impulse and Change in Momentum
1) A 100 g baseball travels at 90 mph (40 m/s) [east] toward the catcher who catches it.
a) What is its initial momentum?
b) What is its final momentum?
c) If the glove stops the ball in 0.1 seconds, what is the force exerted by the glove on the ball?
2) Determine the momentum of each of the following “systems” initially:
a) A 30 kg girl running at 4 m/s [East] jumps on a 15 kg wagon traveling at 2 m/s [East].
b) A 30 kg girl running at 4 m/s [West] jumps on a 15 kg wagon traveling at 2 m/s [East].
3) A car weighs 7840 N,
a) What is its mass?
b) The car's velocity is 25 m/sec eastward. What is its momentum?
c) The car was accelerated from rest to 25 m/sec by a force of 1000 N. How long did the
force act to give it this velocity?
4) A car of mass 1100 kg moves at 22 m/sec. What braking force is needed to bring the car to a
halt in 20 sec?
5) A force of 6 N [west] acts on a body for 10 sec.
a) What is the impulse acting on the body?
b) What is the body's change in momentum ?
c) The mass of the body is 3 kg, what is its change in velocity ?
6) A 0.40 kg ball travels toward the wall at a speed of 10 m/s. If it bounces back at 5 m/s, what
is its change of momentum?
7) A net force of 2000 N acts on a rocket of mass 1000 kg. How long does it take this force to
increase the rocket's velocity from 0 m/sec to 200 m/sec up?
8) A snow-scooter has a mass of 250 kg and is traveling east at
a speed of 8 m/s. A force acts upon it to the east, as shown in
the graph below.
Force versus Time
150
b) What is the change in the momentum of the scooter in
the first 7 seconds?
Force (N)
100
a) What is the impulse on the scooter in the first 7 seconds?
50
0
0
1
2
3
4
5 6 7
Tim e (s)
c) What is the velocity of the scooter at the end of 7
seconds?
6/27/2017
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Momentum and Collisions
1. A plastic ball of mass 0.2 kg moves with a velocity of 0.30 m/s [R]. This plastic ball collides
with a second plastic ball which has half the mass of the first ball. The second ball is moving in
the same direction as the first, but has a speed of 0.10 m/s. After the collision, the second ball has
a velocity of 0.28 m/s [R]. What is the final velocity of the first ball?
2. An ivory ball of mass 100 g is moving at a velocity of 20 cm/s to the right. It collides with a
second ball with a mass of 200 g, which is moving at 10 cm/s to the right. After the collision, the
first ball is slowed to 5 cm/s to the right, what is the final velocity of the second ball?
3. A 5 kg glider moves along an air track with a velocity of 0.8 m/s [L]. It collides with another 5
kg glider which is stationary. If the originally stationary glider is moving at 0.6 m/s [L] after the
collision, what is the final speed of the first glider?
4. A car of mass 700 kg is travelling at 20 m/s [N] toward an intersection. If it collides with a
stationary truck of mass 1300 kg, and they lock bumpers as a result of the collision. What is the
final velocity of the truck?
5. A bullet of mass 50 g strikes a stationary wooden block of mass 5 kg. The bullet becomes
embedded in the block. The block+bullet then flies forward at 10 m/s. What was the original
velocity of the bullet?
6. A 40 kg cannonball is shot from a 500 kg cannon with a velocity of 200 m/s forward. What is the
recoil velocity of the cannon?
7. Two campers (80 kg each) are sitting in a canoe (20 kg) near the dock. If one camper steps
toward the dock at 4 m/s, what will the final velocity of the other camper and canoe be?
8. A hockey player (95 kg) is skating to the west at 8 m/s. If the puck (170 g), hits the hockey
player head-on travelling at 40 m/s, and the puck is caught by the hockey player, what will the
final velocity of the puck/hockey player be?
Answers:
Momentum, Impulse, and Change in Momentum: 1. a) 4 kg m/s [E], b) 0 kg m/s, c) 40 N [W], 2
a) 150 kg m/s [E], b) 90 kg m/s [W], 3a) 800 kg, b) 20 000 kg m/s [E], c) 20 sec, 4) 1210 N
[backward], 5.a) 60 N s [W], b) 60 kg m/s, c) 20 m/s [W], 6) 6 kg m/s [back], 7) 100 sec, 8.a)
500 N s [E], 500 kg m/s [E], 10 m/s [E]
Momentum and Collisions: 1) 0.21 m/s [R], 2) 0.175 m/s [R], 3) 0.2 m/s [L], 4) 7 m/s [N], 5)
1010 m/s [forward], 6) 16 m/s [backward], 7) 3.2 m/s [backward], 8) 7.91 m/s [W] (not 7.93!!!)