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

# Cart on Cart, 1F30.30

Topic and Concept:

Location:

Abstract:

A small cart is free to move on top of a large rolling cart which comes to a sudden stop. The cart continues to move due to the cart's inertia.

 Equipment Location ID Number Pasco Long Track ME, North Wall Pasco Long Track ME, Bay A3, Cubby 3 Pasco Carts ME, Bay A5, Shelf #2 2 4x4 Wood Blocks By Elevator 2 Pasco Wood Friction Blocks ME, Bay A5, Shelf #2

Important Setup Notes:

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Setup and Procedure:

1. Level the longer track on the table and place a brick by the feet to prevent the track from moving.
2. Place two 4x4 wooden block on the ends of the long track for crash bumpers.
3. Place two cars with small wooden blocks on top, onto the larger track, then place the shorter track on top of these two carts.
4. Position these two cars such that their outermost ends of the smaller track.
5. Place the third car on top of the smaller track.
6. By applying equal force simultaneously to both the top track(thereby setting the bottom two cars into motion) and the top car, set the system in motion from one end of the longer track to the other end.

Cautions, Warnings, or Safety Concerns:

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Discussion:

When the whole system is set into motion, all carts obtain some particular velocity which would remain constant as per Newton's first law if air resistance and friction were not present. When the two carts on the bottom layer and the track resting on top of them collide with the wood block on the end of the bottommost track, they change their velocity. However, the top car remains in motion with its original velocity until reaches the end of the top track, putting a new force on the top car making its net externally applied force nonzero and therefore changing its velocity.

Videos:

References:

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