Here we go...

As always, momentum is conserved.
 
 
 

2.  Consider two low friction carts on horizontal tracks.  The carts are of mass m and 2m.  You first push the lighter car for 3s and then the other for the same length of time, exerting an equal force on each.  The momentum of the light car is...

a. Four times
b. Twice
c. Equal to
d. One-half
e. One-quarter

3.  Imagine that you are at a carnival and you are playing the game where you must knock down a large wooden bowling pin by throwing a ball at it.  You can choose between  a rubber ball or one made of putty, both of the same size and mass.  Which one should you choose?

a. The rubber ball.
b. The ball of putty.
c. Makes no difference.
d. Need more information.

4.  In a boxcar (mass 2000 kg, length 10m), a cannon (mass 200 kg) fires 100 shells (each mass 5 kg, with velocity 50 m/s) at opposite wall.  Find the speed of the car after firing all of the balls.