1. FORCES AND NEWTON’S LAWS
CHAPTER 3

2. I. FORCES – 3.1
What is force?
1. Please Define Force: A push or pull exerted on an object.

3. 2. Changing motion Net force
a. Please Define Net Force: Sum of all the forces that are acting on an object.

4. 4. Unbalanced forces
a. Please Define Unbalanced Force: An unbalance force is one that is not opposed by an equal and opposite force operating directly against the force and causes the object to change its motion.

5. 5. Balanced forces
a. Please Define Balanced forces: Forces are balanced when the forces pushing (or pulling) an object in one direction are the same size as the forces acting in the opposite direction.

6. B. Friction
Please Define Friction: Force that opposes the sliding motion between two touching
surfaces.

7. 2. What causes friction?

8. 3. Static Friction
a. Please Define Static Friction: Frictional force that prevents two surfaces from sliding past each other.

9. 4. Sliding Friction
a. Please Define Sliding Friction: Frictional force that opposes the motion of two surfaces past each other.

10. 5. Rolling Friction
a. Please Define Rolling Friction: Rolling friction is a resistive force that opposes the rolling motion of an object.

11. C. Gravity The law of universal gravitation
a. Write the Equation for Universal Gravitation:
F = G m1m2 d2

12. b. Gravity and you The range of gravity The gravitational field
(1.) Please Define Field: A region of
space in which every point has
a physical quantity, such as a force.

13. 2. Weight
Please Define Weight: Gravitational force exerted on an object.
Write the Equation for Weight:
Fg = mg
Weight (N) = mass (kg) x gravitational strength (N/kg)

14. c. Weight and mass
(1.) Please Define Weight: Gravitational force exerted on an object. (2.) Please Define Mass: Amount of matter in an object.

15. d. Weight on Earth (1.) Write the units of “g” in two different ways.
(a.) 9.80 m/s2
(b.) N/kg
Weight away from Earth
3. Finding other planets

16. II. NEWTON’S LAWS OF MOTION -3.2
A. Isaac Newton and the Laws of Motion

17. B. Newton’s First Law of Motion
Please Define Newton’s First Law of Motion:
That an object moving at a constant velocity
keeps moving at that velocity unless an unbalanced force acts on it.

18. 2. Inertia
a. Please Define Inertia: Tendency of an object to resist any change in its motion.

19. 3. Inertia and mass

20. C. Newton’s Second Law of Motion
Force and acceleration
Mass and acceleration
Relating force, mass, and acceleration
a. Please Define Newton’s second law of motion: That the acceleration of an object
is in the same direction as the net force on
the object, and that the acceleration equals the net force exerted on it divided by its mass.

21. c. Calculating net force
(1.) Please write net force as an Equation: Fnet = mass x acceleration

22. D. Newton’s Third Law of Motion
Please Define Newton’s Third Law of Motion:
That when one object exerts a force on a second object, the second object exerts a force on the first object that is equal in strength and in the opposite direction.
Or for every action there is an equal and opposite reaction.

23. Forces on different objects do not cancel
Forces are interactions

24. III. USING NEWTON’S LAWS -3.3
What happens in a crash?
a. Safety belts
b. Air bags

25. b. Air bags

26. B. Newton’s Second Law and Gravitational Acceleration
Air resistance
1. Please Define Air Resistance:
Force that opposes the motion of objects
that move through the air.

27. 2. Size and shape

28. 3. Speed and terminal velocity
Please Define Terminal Velocity:
The maximum speed an object will reach
when falling through a substance, such as air.

29. b. Free fall Please Define Free Fall:
Describes the fall of an object on which
only the force of gravity is acting.

30. 2. Weightlessness

31. C. Centripetal Forces Please Define Centripetal Force:
A force that is directed toward the center
of a curved or circular path.

32. D. Force and Momentum Conservation of momentum
a. Please Define the Law of Conservation of Momentum:
That if no external forces act on a group of objects,
their total momentum does not change.

33. b. Collisions with multiple objects

34. 2. Rocket propulsion

35. IV. CHAPTER 3 REVIEW
Please do Check Concepts 34-42, found on page 98 in your Text.
Please do Standardized Test Practice 1-8, found on page 100 in your Text.
I will give you a Pre-Test on Chapter 3 problems for your Chapter 3 Test.