1. May the Force Be With You!

2. What is FORCE? A push or pull on an object
Causing resting objects to move
Causing moving objects to accelerate

3. Two Main Force Types Balanced Forces Unbalanced Forces Two Forces
Opposite directions
Both are equal in value
No movement (stationary)
Unbalanced Forces
Two Forces
One greater than the other
Opposite directions
Movement

4. Newton’s 3 Laws of Motion

5. 1st Law of Motion The Law AKA
Objects at rest remain at rest or objects in motion remain in motion unless acted on by a force
AKA
Law of INERTIA

6. 1st Law of Motion
Inertia—force that is resistant to the direction of motion
Concept—unbalanced forces
Ex:
inertia belts (seat belts)
Space ships going through space

7. 2nd Law of Motion The Law Concept AKA
The acceleration of a body depends on the ratio of the acting force to the mass of the body
Concept
Unbalanced forces
AKA
The force formula

8. F= force (unit = Newton) a= acceleration (unit m/s2
Force Formula
Force = mass * acceleration
F= m*a
F= force (unit = Newton)
m= mass (unit = kg)
a= acceleration (unit m/s2

9. Force Example Problems
#1 How much force is needed to accelerate a 500-kg car at a rate of 4 m/s/s?
#2 A 50-kg object is accelerating at a rate of 2 m/s/s, what is the force that caused this acceleration?

10. 3rd Law of Motion The Law Concept Ex Remember, forces are equal
For every action there is an equal but opposite reaction
Concept
Balanced Forces Ex
Stationary Objects
Rockets being launched
Remember,
forces are equal
but opposite

11. Applying the 3rd Law
If Rico kicked a ball with 100-N of force, how much force did the ball exert on Rico?

13. What is Friction? Is a force that resist motion and can cause heat
Allows us to walk, drive a car, play sports
Lubricants help reduce friction

14. 4 Types of Friction Rolling Friction Static Friction Fluid Friction
Friction acting on objects that are rolling
Ex: car tired
Fluid Friction
Friction acting on objects going through a fluid
Fluid—liquid or gas
Ex: swimming or air resistance
Static Friction
Friction force on stationary objects
Ex: book sitting on desk
Sliding Friction
Friction acting on objects sliding over a surface
Ex: pushing a box

15. ID the type of Friction

16. What is Gravity? A force that acts between masses Acts downward
Acceleration due to gravity (on Earth)= 9.8 m/s/s

17. What is Air Resistance? Force that slows down falling objects Factors
Atmosphere
Surface area of object
Acts upward

18. Gravity and Air Resistance: A Relationship
They are opposite forces
Gravity goes down
Air resistance acts up
Follows Newton’s 3rd Law of Motion

19. Feather vs. Rock EARTH Moon or Vacuum Feather floats down
Rock falls at 9.8 m/s/s
Why?
Air Resistance
Moon or Vacuum
Feather and rock fall at the same rate
WHY?
No air so no air resistance

20. Projectile Motion The motion of falling objects throw forward
Two forces
Gravity
Forward velocity
Gravity acts down
Velocity acts forward
Forms a curve path

21. Weight Is the force of gravity acting on an object
Weight Formula
Weight = mass * gravity
Fg = m * g
Fg= weight (unit = N)
m= mass (unit = kg)
g= gravity (9.8 m/s/s)

22. Weight Example Problems
#1 If a 20 kg dude is on Earth, what is his weight?
#2 A rock on Earth has a weight of 1000 N, what is the rock’s mass?