1. 11.8 Forces Review

2. Define Force
A force is a push or pull on an object.

3. What piece of equipment is used to measure force?
A “Spring Scale” is used to measure force.

4. What units are used to measure force?
Newton's

5. What is a normal force?
A upward force from an object sitting on a surface. This force is always perpendicular to the surface.

6. What is a Tension Force?
A force from pulling on an object.

7. When will forces cause an object to change motion?
When the net forces on an object are unbalanced.

8. When will forces not cause an object to change motion?
When the net forces on an object are balanced.

9. Define Friction
The force that opposes motion of objects that touch as they move past each other.

10. What are the two factors that affect friction?
Type of surface or material
The force pushing the surfaces together

11. Define the four types of friction
Static Friction
Friction of objects that are not moving
Sliding Friction
A force that opposes motion as it slides over a surface
Rolling Friction
The friction force that acts on rolling objects
Fluid Friction
Opposes the movement of an object through a liquid or a gas

12. List the types of friction in order from weakest to strongest
Fluid (Weakest)
Rolling
Sliding
Static (Strongest)

13. What is air resistance? What type of friction is air resistance?
A force that acts on an object as it moves through the air.
Air resistance is fluid friction

14. How does gravity and air resistance work on a falling object?
Gravity pulls the object down
Air resistance pushes up

15. Define Gravity
A force that acts downward toward the center of the earth

16. Define Weight
The force of gravity acting on an object

17. Define Terminal Velocity
A constant velocity when the gravitational force and the air resistance force is equal

18. Which individual started the study of force, but much of his theories were wrong?
Aristotle

19. Which individual studied how gravity produces constant acceleration and object would continue moving forever if they were not subjected to a force?
Galileo

20. What is Newton’s 1st Law of Motion. Define it.
Law of Inertia
An object in motion wants to stay in motion and an object at rest will stay at rest unless acted on by an outside force.

21. Define Inertia
The tendency of an object to resist a change in motion

22. What is Newton’s 2nd Law of Motion? Define it.
Law of Acceleration.
The Force of any object is a product of its mass and acceleration (F = m x a).

23. What is Newton’s 3rd Law of Motion? Define it.
Law of Interaction
For every action there is an opposite and equal reaction.

24. What is the difference between mass and weight?
Weight : The force of gravity acting on an object
Weight = m x 9.8 m/s2
Mass: Measured by the inertia of an object

25. Tell the “net force” (direction included) of each box
A = 400 N upward
B = 200 N downward
C = No Movement

26. …..
Look thru your packet and understand how to do force problems using the formulas.

27. Any Questions!!!!
Quiz Tomorrow!
Good Luck and Study !!