Some common types of forces that you will be dealing withinclude the gravitational force (weight), the force of tension, theforce of friction, and the normal force.

It is sometimes convenient to classify forces as either “contactforces” between two objects that are touching or as “long-rangeforces” between two objects that are some distance apart. Contactforces include tension, friction, and the normal force. Long-rangeforces include gravity and electromagnetic forces. Note that such adistinction is useful but not really fundamental. For instance, ona microscopic scale the force of friction is really anelectromagnetic force.

In this problem, you will identify the types of forces acting onobjects in various situations.

Now consider a different situation. A string is attached to aheavy block and is used to pull the block to the right along arough horizontal table.

What is the upward force that acts on the book called?

 

Which object exerts a force on the block that is directed to theright?