Sliding friction

The three investigations done in class this week has led us to discover that:

• The force of sliding friction depends on the type surface it is moving across.
• The force of sliding friction increases as the weight increases.
• The force of sliding friction does not depend on the surface area of the block in contact with the surface.

You used a spring scale to measure the force that counterbalanced the frictional force. This was evident when you pulled on the scale at a steady rate. Your effort force is equal to and opposite the frictional force. (Newton's Third Law!)

We also discussed another type of friction- air resistance. Keep in mind the variables you tested in class would affect objects differently in the air. (Surface area matters when you are flying through the air!)

Reminder: HW list and lab reports are due tomorrow!