If A $2.0 \mathrm{~kg}$ puck is moving east at $5.5 \mathrm{~m} / \mathrm{s}$. It catches up to and collides with a second identical puck moving due east at $3.0 \mathrm{~m} / \mathrm{s}$. The collision is perfectly inelastic.

a. What is the resulting velocity of the pucks?
b. What is the initial kinetic energy $E_{k i}$ of the system?
c. What is the change in kinetic energy, $\Delta E_k$, of the system as a result of the collision?
d. If the mass $m$ is doubled, but the initial velocities are unchanged, does the resulting velocity increase, decrease, or remain unchanged?

A $3,000 \mathrm{~kg}$ truck is traveling $28 \mathrm{~m} / \mathrm{s}$ through a rainstorm. At the end of its journey, it has collected $500 \mathrm{~kg}$ of water and is now moving $24 \mathrm{~m} / \mathrm{s}$. Was momentum conserved?

Consider two bowling balls, each with a mass of $4.0 \mathrm{~kg}$. The red ball is moving east at $2.0 \mathrm{~m} / \mathrm{s}$. The blue ball is moving west at $1.0 \mathrm{~m} / \mathrm{s}$. Calculate the total momentum of the system.

If it's raining in the early morning, can we see a rainbow if we look east? Explain.

If In an elastic collision, a $1.0 \mathrm{~kg}$ ball moving at $1.0 \mathrm{~m} / \mathrm{s}$ collides with a $2.0 \mathrm{~kg}$ ball moving at $-2.0 \mathrm{~m} / \mathrm{s}$. The $2.0 \mathrm{~kg}$ ball transfers all of its momenta to the $1.0 \mathrm{~kg}$ ball.
a. What velocity does the $1.0 \mathrm{~kg}$ ball have after the collision?
b. What is the initial kinetic energy of the system?
c. What is the final kinetic energy of the system?

A $1,200 \mathrm{~kg}$ car is heading due north at $14.0 \mathrm{~m} / \mathrm{s}$. It collides with an identical car heading due south at $14.0 \mathrm{~m} / \mathrm{s}$. What is the combined momentum of the cars before the collision?

Calculate the magnitude of the change in momentum in each of the following examples.
a. A $1,200 \mathrm{~kg}$ car accelerates from rest to a speed of $20 \mathrm{~m} / \mathrm{s}$.
b. A $75 \mathrm{~g}$ pellet moving at $18.0 \mathrm{~m} / \mathrm{s}$ hits a tree and lodges in it.
c. A $250 \mathrm{~g}$ rubber ball hits the floor at $10.0 \mathrm{~m} / \mathrm{s}$ and rebounds at $6.0 \mathrm{~m} / \mathrm{s}$.
d. A $60 \mathrm{~kg}$ student jogging at $3.0 \mathrm{~m} / \mathrm{s}$ speeds up to $6.5 \mathrm{~m} / \mathrm{s}$.

Calculate the momentum of a $75 \mathrm{~kg}$ person running at $10 \mathrm{~m} / \mathrm{s}$.

A $10 \mathrm{~kg}$ bowling ball sits at the top of a $10 \mathrm{~m}$ hill and then slides down its icy hillside.
a. What is the speed of the bowling ball when it reaches the bottom of the hill?
b. What is the change in kinetic energy of the system as the bowling ball travels from the top of the hill to the bottom of the hill?
c. What is the bowling ball's mechanical energy at the top of the hill?
d. What is the bowling ball's mechanical energy at the bottom of the hill?

You can only apply a $200 \mathrm{~N}$ force but you need to make a $20 \mathrm{~kg}$ wagon of mulch travel at a speed of $10 \mathrm{~m} / \mathrm{s}$. How far do you have to push the wagon before its speed reaches $10 \mathrm{~m} / \mathrm{s}$ if it starts from rest? You may assume no friction.

How much distance does it take to stop a car going $30 \mathrm{~m} / \mathrm{s}(67 \mathrm{mph})$ if the brakes can apply a force equal to one half the car's weight?

John weighs $80 \mathrm{~kg}$, and eats a $1,000$ J candy bar. If his body perfectly transforms the energy in the chocolate into kinetic energy, what is the fastest he can run?

A boy walks up a 10-meter-tall snow-covered hill and sleds down. When he reaches the bottom, the boy is moving at $7 \mathrm{~m} / \mathrm{s}$. What is the efficiency of the boy's sled ride?

A $60 \mathrm{~kg}$ diver jumps off a diving board upward with an initial velocity of $5 \mathrm{~m} / \mathrm{s}$. The diving board is $10 \mathrm{~m}$ higher than the water. What is the diver's speed when just entering the water after the dive?