In the situation above, a small projectile is fired into the oncoming rail car. The projectile will impact the rail car, transfer momentum and stick to the rail car (therefore increasing its mass).

Investigation:

1. Fire one shot and note the velocity what must the mass of the projectile be? Hit reset and test this by changing the momentum with the slider bar and repeat the observation.

2. Hit reset and set the momentum back 100. How many shots will it take to reduce the velocity of the rail cart to zero? Test your hypothesis.

3. Hit reset and decrease the mass of the rail cart to 50. Now how many shots will it take?

4. Reset the rail cart mass to 100 and change the momentum to 1000. What will happen to the rail cart after the first shot? (make a guess or estimate, and then shoot). What is the predicted velocity of the rail cart after the second shot?

   In this case we have two rail carts that will move towards each other and collide and stick.

   Investigations:

   1. Determine the mass of the first cart. You will have to adjust the momentum of the first cart and run a few trials and make a few observations. Note, the value in the Target Velocity will change when the carts stick and it will appear above the second cart. The velocity above the first cart is its initial velocity, retained for reference.

   2. Hit reset and set the momentum to 200. What is your predicted value for the final velocity of the coupled carts?

   3. Hit reset, leave the momentum to 200 but raise the mass of the cart to 100 What is your predicted value for the final velocity ?

   4. Finally, raise the momentum to 400 What must the mass of the second cart be in order for the final velocity to be zero?

      In this case, things are considerably more complicated. The rail carts will collide and bounce off one another.

      Investigation:

      1. Adjust the target mass so that after the collision both carts are at rest. What is this target mass?

      2. Leaving the target mass at this value, reduce the momentum to 200? What is our predicted qualitative behavior of the carts? Confirm that momentum has been conserved by using the final velocities of the two carts.

      3. Now set the momentum of the first cart to be 800. Again what is your qualitative prediction on the behavior and confirm that momentum has been conserved.

      4. Finally, if the cart masses are equal, what do you think the behavior will be, regardless of the momentum? Test your assertions.