Introduction

You have no doubt explored conservation of momentum during collisions between objects moving in one dimension (linear motion), such as when carts on a track collide. You may have also studied the concept of conservation of angular momentum. Perhaps you conducted a classic experiment involving dropping a disk or ring onto a rotating disk and observing the change in angular velocity. In this activity you are going to explore a collision between a physical pendulum and a cart on a track. The first clearly has angular momentum and the second clearly has linear momentum. But are those momentums equal? In other words, is momentum conserved in a collision involving a rotating rigid object if the object with which it collides moves linearly after the collision?

In the first part of this activity you will investigate the conservation of linear momentum of the physical pendulum and the cart. Then you will explore the conservation of angular momentum of these objects relative to the point of rotation of the pendulum.

Objectives

  • Use video analysis techniques to determine the linear momentum of a cart and a point on a physical pendulum.
  • Use video analysis techniques to determine the angular momentum of a physical pendulum.
  • Use video analysis tools to determine the angular momentum of a “point object” in 1‑dimensional motion.
  • Evaluate the conservation of linear and angular momentum as an object in circular motion collides with a stationary object, causing it to move linearly.