Simulations
This applet has some great tools to learn about friction. Near the top of the applet there is a tab that says friction; open that. Start by just applying a small force. Watch what happens to the force of friction as you increase the applied force? What happens when the applied force gets very big? After static friction is broken what can we say about the magnitude of the force of friction as the block slides around?
Now try the same thing, but with a ramp;
Other Activities
An online workbook provided by PhysicsLAB;