1. Forces
Chapter 3

2. Force of Gravity Lab
Does the speed of a falling object depend on the object’s mass?
P. 67

3. Relationship of Force & Acceleration
The greater the force, the greater the acceleration

5. The smaller the mass, the greater the acceleration

6. Newton’s Second Law
The acceleration of an object is in the same direction as the net force, and the acceleration can be calculated from the following equation:

7. Force = mass x acceleration

9. Calculate the force need to move a 5kg box with an acceleration of 2
Calculate the force need to move a 5kg box with an acceleration of 2.5m/s2

10. sofia

11. Calculate the force need to move a 3kg book with an acceleration of 4
Calculate the force need to move a 3kg book with an acceleration of 4.3 m/s2

12. Calculate the mass of an object that accelerates at a rate of 3 m/s2 when it is pushed with a force of 9 Newtons.

13. Calculate the acceleration of a 6
Calculate the acceleration of a 6.1 kg object is pulled with a force of 30.5N

14. Friction
The force that opposes the sliding motion of two surfaces that are touching eahc other
depends on 2 factors
Kind of surfaces
Force pressing between them

16. 3 types of friction
1. Static friction: the force that prevents two surfaces from sliding past each other

17. 2. Sliding friction: force that opposes the motion of two sliding past each other

18. 3. Rolling friction: force between a rolling object and the surface it rolls on

19. Air Resistance
Friction-like force that opposes the motion of objects that move through air
Size, shape, speed, affect the amount of air resistance

20. Air Resistance (cont)
Without air resistance, all falling objects would accelerate equally

21. Feathers
Ball
slow motion

22. Terminal Velocity
The force of air resistance equals the force due to gravity
Object’s fastest speed
The object no longer accelerates and remains at the high constant velocity

23. Gravity An attractive force between any two objects
It depends on the masses of the objects and the distance between them

24. Gravity
The greater the mass,
the greater the force

26. The earth’s mass is so
great, that we can observe
its force of gravity on us.

27. gravity

28. Comparing Friction!
Object
Height (cm)
Type of Friction Observed

29. Weight- gravitational force on an object
Weight= mass x acceleration due to gravity

31. Weightlessness
Weightlessness exists when you are in free fall

33. Projectile Motion
The path of an object(projectile) with the force of gravity
Gravity adds the vertical motion

37. Observing Air Resistance

38. Centripetal Force
Acceleration towards the center of a curved or circular path is centripetal acceleration
The net force exerted toward the center of a curved path is centripetal force.

39. Newton’s 3rd Law of Motion
Every action force has an equal and opposite reaction force

42. Momentum= mass x velocity
The property of a moving object that is the product of its mass and velocity
Related to how much force is need to change the object’s motion
Momentum= mass x velocity

43. What is the momentum of a 7kg ball traveling at a velocity of 3.1 m/s?
p = 7kg x 3.1 m/s
P = kg m/s

44. What is the mass of a truck that has a momentum of 43,200 kg m/s and a velocity of 24m/s?

45. p. 86 #1-3

46. Force and Changing Momentum
Force =
Force = mass x acceleration
Force = mass x velocity

47. Law of Conservation of Momentum
Momentum within a system is transferred, not changed.