Concepts

Kinetic and static friction

Overview

Show that static friction is greater than kinetic friction by pulling on a wooden box using a spring scale.

This can also be done on the computer using Logger Pro and a force probe.

Details

Equipment

• [1] Wooden box with metal slipper
• [1] Steel brick
• [1] 40 N spring scale or force probe
  
• [1] Wooden board
• [2] C-clamp
• [1] (Optional) Computer with LabQuest Mini and Logger Pro

Classroom Assembly

1. Clamp the board to a table.
2. (Optional) Select the 50 N scale on the force probe and connect it to the computer.
   

Important Notes

• The steel brick is a bit heavy. Handle with care.

Script

1. Put the box on the board.
2. Put the brick in the box.
3. Pull on the box with the 40 N scale or force probe, careful to let students see the reading. Slowly increase the force until the box starts moving, then decrease the pulling force so that the box moves at constant velocity.

Additional Resources