Fan Cart and Motor Cart

Fan cart facing sonic ranger on track
Fan cart final setup


The motion of different types of carts on a track, one with a fan that creates a constant acceleration, the other with a motor that creates a constant velocity, can be graphed onto a classroom computer by a sonic ranger. Weights are available for adjusting the mass of the carts.


The purpose of the fan cart demonstration is to show students that a constant force implies a constant acceleration. The motor cart, which moves at a constant velocity, is available for comparison. Both demonstrations use Logger Pro.


  • Track
  • Fan cart
  • Motor cart
  • 2 weights
  • Fan attachment
  • Sonic ranger
  • Computer

All of these parts (with the exception of the computer) are located in room 202, the lecture prep demonstration room. The track is located above shelves D and E, and is visible when you walk into room 202. The carts, weights, and fan attachment are located on shelf A1. The sonic ranger is located on shelf K2, and its cord is wrapped around a wooden block.


Put the track on a flat surface and adjust the legs of the track to make sure it is even. If a level is not available, put the fan cart on the track and adjust the track legs until the cart no longer rolls forward or backward.

Place the sonic ranger on top of the wooden block on one end of the track. Plug the sonic ranger’s cord into the USB port of a computer that has Logger Pro installed on it, which should be any classroom computer in Thompson.

For fan cart: Clip fan onto cart. Fan needs to be placed at the front or back end of the cart so that the blades do not hit the cart. Weights can be placed on top of the cart beneath the fan. Place cart on track, with fan attachment facing sonic ranger.

For motor cart: Place motor cart onto track, weights can be added on top of the cart.

How it works:

Open up logger Pro and click the green “Go” button to make the sonic ranger collect data. When the fan car (with the fan attachment) is on the track, turn on the fan by pressing the red button on top of the attachment. This button will also turn the fan off. To use the motor cart, flip the switch on top of the cart. There is a small dial next to this switch for adjusting the speed of the motor cart. Logger Pro will display graphs showing the motion of the carts.