Optional Practical: 1D momentum (Algodoo)

In this exercise the momentum of two colliding carts will be investigated but first you need to build the carts. If you have done the motion in Algodoo exercise then you already know how to do this if not refer to that worksheet (Motion of a cart in Algodoo) Note: the wheels must not protrude outside the rectangular body of the cart, as shown below.

You are going to try many different collisions so will be changing the properties of the carts many times, to make this easy right click the left hand cart (just the body) and select material then drag the box and place it above the cart, it will now stay there while you run your experiments. Do the same with the velocity box then repeat for the right hand cart.

Elastic collisions

  • Set the restitution of both carts to 1. (this means that kinetic energy will be conserved)
  • Set the velocity of the left hand cart to 1 ms-1
  • Run the animation and observe how the momentum of the carts change but the total momentum is constant. (since the mass of both carts is 1 kg the momentum is numerically equal to the velocity)
  • Display momentum vectors by ticking momentum at the bottom of the velocity box on each cart.
  • Try different masses and velocities.

Inelastic collisions

  • Set the restitution of both carts to 0. (kinetic energy is no longer conserved)
  • Try some different inelastic collisions.
  • To make the carts stick together add some attraction to each cart (about 0.5 Nm2kg-2 works for slow collisions but you can experiment with different values)
  • Try adding more carts.
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