Jamie pushes a book off a table. the push is an example of a contact force because a. jamie used energy. b. jamie had to touch the book to move it. c. the book fell to the floor. d. the book was on a flat surface.

Explanation :

Contact forces are the forces that act between the objects that are in contact.

When James pushes a book off a table, the push is an example of a contact force. This is because Jamie had to touch the book to move it. For experiencing a contact force, there should be contact between two objects.

The examples of contact forces are the frictional force, tension force, normal force etc.

While gravitational force, electric force and the magnetic force are non contact force.

So, the correct option is (B) " Jamie had to touch the book to move it ".

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle