Ball and Cart: Observational Experiment

Aim

To understand the motion of projectiles

Prior Knowledge

  1. Understanding of motion with constant velocity.
  2. Understanding of motion of falling objects.
  3. Reference frames.
  4. Newton's laws.

Description of the Experiment

For all the three trials together:

Observe the motion of the ball and the cart and describe what you observe in simple words.

Youtube movies can be stepped frame by frame using the , and . keys on your keyboard. If you want to download the movie to your computer, right-click or control-click HERE.

Questions

  1. Why do you think the ball always returned to the cart? Devise as many explanations as possible.
  2. How can you test each explanation? Propose a testing experiment for each.

More detailed analysis for each of the three trials:

  • Observe the motion of the cart with respect to the table. Stepping the video frame by frame, draw a motion diagram representing the motion of the cart. Describe in words the motion of the cart relative to the table
  • Observe the motion of the ball with respect to the cart. Stepping the video frame by frame, draw a motion diagram representing the motion of the ball with respect to the cart. Describe in words the motion of the ball relative to the cart
  • What can you say about the motion of the ball and the cart with respect to each other in each trial?
  • Observe the motion of the ball with respect to the table. Stepping the video frame by frame, draw a motion diagram representing the motion of the ball.
  • Discuss with your group: How are the motion of the cart with respect to the table and the motion of the ball with respect to the cart related to the motion of the ball with respect to the table?