Exploring friction with a Smart Cart

What are some good experiments into friction that can be run with a Smart Cart?

If you are exploring the concept of friction with your students, we have the following equipment to help with the exploration of velocity independent friction (static or kinetic friction), friction dependent linearly with velocity, and air drag (friction dependent on the square velocity of the cart).  The following equipment can be helpful for these investigations.

1.  Discover Friction Accessory

When these are dragged by the force sensor on the Smart Cart, you get both the frictional force and the velocity, so that you will be able to get the clear onset of the kinetic vs. static friction. It may be helpful to plot the frictional force vs. velocity. This will lock the static friction to the vertical axis until the cart starts to move, and the frictional force will drop to the kinetic value and stay close to that value as long as the tray is not experiencing a high acceleration (this will increase the force applied to the tray above the kinetic frictional force.

2. Dynamics Cart Magnetic Damping

This will have a linear dependence on the speed of the cart. The magnitude of the damping force can be measured since the accessory is attached to the magnetic bumper accessory for the Smart Cart.

3. Car Sail 

The sail will impart a frictional force proportional to the velocity of the cart squared.