2.  When the net force equals O N, forces are said to be ________________.

3.  What is the SI unit for force?

4.  What type of force causes an object to begin moving?

5.  What is the net force when Ted is pulling a rope to the right with a force of 525 N and Bill is pulling the rope to the left with a force of 500 N?

6.  Using the previous question’s example answer the follow questions: *The forces were working together or opposite forces? *The forces were equal or not equal? *The forces did or did not balance each other out? *There was motion or no motion?

7.  List the three types of kinetic friction.

8.  A force that opposes motion between two surfaces in contact is called ________________.

9.  A force applied to an object but does not cause the object to move is called ______________.

10.  List one example of when friction is helpful and one example of when friction is harmful.

11.  List one example of a way to increase friction and one example of a way to decrease friction.

12.  1. balanced  2. Newtons  3. an unbalanced force  4. 25 N right  5. *opposite forces *not equal *did not balance *was motion  6. sliding, rolling, and fluid  7. friction  8. static friction  9. helpful=walking, stopping a car harmful=friction in car engines wearing down parts.  10. increase=make surface rougher, apply more force decrease=make surface smoother, sliding-rolling, lubricants