Chapter 3 Homework #1
Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two- ball system?
0 kg•m/s
Two identical freight cars roll without friction towards each other on a level track. One car rolls at 2 m/s and the other car rolls at 1 m/s. After the cars collide, they couple and roll together with a speed of
0.5 m/s.
A 1000-kg truck moving at 10 m/s that brakes to a stop in 5 s has an average braking force of
2000 N
Find the momentum for a 2.8-kg brick parachuting straight downward at a constant speed of 8.6 m/s.
24.08 kg-m/s
What is the speed of a 4-kg ball with a momentum of 12 kg•m/s?
3 m/s
Find the impulse on a baseball that is hit with 100 N of force in a time of 0.46 s.
46 N•s
A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car?
6 m/s
A boxer punches a sheet of paper in midair from rest to a speed of 40 m/s in 0.05 s. If the mass of the paper is 0.01 kg, the force of the punch on the paper
8.0 N
For each crate, rank changes in momentum from greatest to least.
A, B, C
For each crate, rank momenta at the end of 3 s from greatest to least.
A, B, C
Starting from rest, Marshall pushes crates across the floor of his classroom for 3 s with a net force as shown in the figure below. For each crate, rank impulses delivered from greatest to least.
A, B, C
Rank the impulses needed to stop the balls from greatest to least.
B, D, C, A
The balls have different masses and speeds. Rank momenta from greatest to least.
B, D, C, A
For each crate, rank final speeds from greatest to least.
C, B, A
The impulse-momentum relationship is a direct result of
Newton's second law.
Which has more momentum after firing, the cannonball or the recoiling cannon?
They are both the same
Which of the following has the largest momentum relative to Earth?
a pickup truck speeding along a highway
When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, the contact is about 10 times more than for a stiff-legged landing and the average force your body experiences is reduced by
about 10 times
When you simultaneously drop a light tennis ball and a heavy bowling ball, they hit the floor
at the same speed.
While driving down the highway a lovebug spatters onto your windshield. Which undergoes the greater impulse?
both the same
While driving down the highway a lovebug spatters onto your windshield. Which experiences the greater force of impact?
both the same but with different consequences
When the speed of an object is doubled, its momentum
doubles
When you can't escape being hit by a fast-moving object, you'll suffer a smaller force if the collision time is
long.
Compared with falling on a wooden floor, a wine glass may not break when it falls on a carpeted floor because of
longer time to stop.
When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to differences in
masses.
A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater
momentum.
It is correct to say that impulse is equal to
the change in momentum.
To catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the
time of catch is increased.
The distinction between impulse and force involves the
time the force acts.
