Video: Instructor’s video
Description: This apparatus shows how the frictional force depends on weight.
- Friction box (see photo)
- Newton Scale
- Set of masses
- Piece of fabric
- Tie a string to the handle of the box, and make a loop at the other end for the scale.
- Make sure all the equipment is in working order.
- You can pull the scale slowly to show the maximum force of static friction.
- You can also pull with constant velocity to show the magnitude of kinetic friction.
- By changing the mass inside the box, you can show that the forces of static and kinetic friction are both proportional to the normal force.
Tips: The newton scale needs to be pulled with a almost constant force to read it.
Concepts: This demo shows the dependence of static and kinetic friction on the normal force applied to a surface. It also shows the difference between static and kinetic friction and demonstrates friction’s dependence on the surface the force is applied to.