Concepts

Coefficient of friction

Overview

To measure the coefficient of static friction, change the angle on a ramp until a small wooden box slides downslope. One can change the contact surface to metal, add moisture, and change the weight of the box.

Details

Equipment

• [1] Wooden box with metal slipper
• [1] Steel brick
• [1] Wooden board
• [1] Sponge
• [1] Water bottle
• [2] Metre stick
• [1] Lab stand
• [2] 90-degree clamp
• [2] 3-finger clamp

Classroom Assembly

1. Place the ramp on a table. 
2. Mount a metre stick vertically next to the ramp using the lab stand, 90-degree clamps, and 3-finger clamps.
3. Place a metre stick horizontally next to the ramp.
4. Put the box on the ramp with metal slipper on and the steel brick inside.

Important Notes

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

Script

1. Ask for a volunteer to help you measure the angle at which the box starts slipping down the ramp.
2. Slowly lift one end of the ramp until the box starts slipping.
3. Put down the ramp and repeat the experiment for a different mass or surface, if desired.

Additional Resources