Table of Mechanics Demonstration List of Mechanics Equipment & Supplies Lecture Demonstrations

# Ball on Cart, 1F30.31

Topic and Concept:

Location:

Abstract:

A ball is placed on a larger cart or dolly, the two being brought to a constant speed. When the larger cart is brought to a sudden stop, the ball flies forward with the original speed in the same direction due to the ball's kinetic inertia.

 Equipment Location ID Number Basketball ME, Bay A2, Shelf #5 Medicine Ball ME, Bay A1, Shelf #1 Cart Floor Item: Various Locations

Important Setup Notes:

• N/A

Setup and Procedure:

1. Place the ball with attached stabilizer(ie, large washer) on the cart.
2. Slowly accelerate the system to desired velocity.
3. Abruptly stop the cart using the rope or your foot or brick.

Cautions, Warnings, or Safety Concerns:

• Be careful when stopping the cart. You could injure a toe or two.

Discussion:

As per Newton's first law, an object in motion tends to stay in motion continuing in a straight line. This is precisely what happens. The ball is held on the cart while the ball - cart system is accelerated to the desired velocity. When the cart suddenly stops, the ball "wants" to maintain this velocity (speed and direction). Thus, the ball flies off the cart. It would remain traveling with this speed and direction if gravity and the non-conservative forces like air resistance were not acting on the ball.

Videos:

References:

• N/A

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