1. Force, Motion and Energy

2. Force Any push or pull on an object Act in pairs
Measured in Newtons (N)
Every force has a magnitude and direction
Forces can work together or against each other
Forces can be balanced or unbalanced

3. Balanced Forces Occurs when there is NO CHANGE in an objects motion
No acceleration – no change in motion
objects are at rest or traveling at a constant speed and direction.

4. Balanced forces

5. Unbalanced Forces Always cause a change in motion - Acceleration
Acceleration – change in speed or direction of an object
Starting
Stopping
Speeding up
Slowing down
Turning

6. Net Force Combination of all forces acting on an object.
Add forces working in the same direction.
Subtract forces that are working in opposite directions.

7. Vectors Lines with arrows that show force.
Length of the line shows the amount of force (magnitude)
The arrow shows the direction of the force.

8. Add forces acting in the same direction
Net Force: 14 Newtons (8+6=14)
Direction of Force: Right

9. Subtract forces acting in opposite directions
Net Force: 2 Newtons (20-18=2)
Direction of Force: Left

10. Net Force = 0 Forces are balanced
Net Force = 0 Newtons (20-20=0)
Forces are balanced - No change in motion

11. Net force and direction
What is the net force?
What is the direction of the force?
Why?

12. Newton’s Law of Inertia
Newton’s 1st Law of Motion
An object at rest will stay at rest unless acted on by an unbalanced force.
And
An object in motion will stay in motion at the same speed and direction unless acted on by an unbalanced force.

13. What does this mean?
Because of inertia, an object will keep doing what it is doing unless forces become unbalanced.
Inertia is an object’s tendency to resist change in motion

14. The car stops but the man keeps going because of inertia
Law of Inertia (1st law)
The car stops but the man keeps going because of inertia

15. Vehicle Restraints
Describe how Newton’s 1st Law of motion applies to vehicle restraints.
Vehicle restraints, such as seat belts, are the unbalanced force that stops you when a car stops suddenly so that you don’t go flying forward.
This applies to all vehicle restraints.

16. Newton’s Law of Acceleration
Newton’s 2nd Law
The acceleration of an object by a force proportional to the mass of the object and directly proportional to the force applied.

17. What does this mean?
The acceleration of an object depends on the mass of the object and the amount of force applied to the object.
Acceleration is any change in motion!!!
Starting, Stopping, Speeding up, Slowing down, and changing directions (turning)

18. In other words…
The less massive an object the greater the acceleration
The more massive an object the smaller the acceleration.
The less force applied the smaller the acceleration
The more force applied the greater the acceleration.

19. Force = Mass X Acceleration
Calculate Force
Force = 1,000 kg X .05 m/s/s
Force = 50 Newtons

20. Practice Calculating Force
Which object would exert the greatest amount of force?
A 500 g object accelerating at 10m/s2 or
A 10 g object accelerating at 10m/s2
Use your formula chart to calculate Force
Force = Mass x acceleration

21. Answer 500g X 10 m/s2 = 5000 Newtons force
10g X 10 m/s2 = 100 Newtons of force
The 500g object exerts a greater force of 5000 Newtons.

22. Acceleration The rate of change in the motion of an object.
includes the velocity, speed and/or direction of an object.
Stopping, starting, speeding up, slowing down and changing directions
How to calculate Acceleration
Acceleration = Force/Mass
Measured in meters/sec2

23. Answer the following Questions
If the mass of an object increases and the force stays the same, what will happen to the amount of acceleration?
Acceleration will Decrease
If the mass of the object decreases and force stays the same, what will happen to the amount of acceleration?
Acceleration will Increase

24. What if the acceleration has to stay the same?
What will have to happen to the amount of force needed if the mass of an object increases?
It would have to INCREASE
What will happen to the amount of force needed if the mass of an object decreases?
It would have to DECREASE

25. Newton’s Law of Action/Reaction
Newton’s 3rd Law of Motion
For every action, there is an equal and opposite reaction

26. What does this mean? All forces act in pairs.
An Action force causes a Reaction force that is equal in size and opposite in direction.

27. Rocket Launches and Newton’s Law of Action/Reaction
A rocket taking off creates an action force of gasses pushing down that causes the reaction force of the rocket going up.

28. Speed
The rate at which an object covers a distance (how fast an object moves)
Calculating Speed
Speed = distance/time

29. Practice Calculating Speed
While on vacation, Lisa Carr traveled a total distance of 440 miles. Her trip took her 8 hours. What was her average speed?
Speed = 440 miles/8 hours
Average speed = 55 miles/hour

30. Velocity Velocity tells an objects SPEED and DIRECTION!!!
It includes the direction an object is moving as well as the distance traveled in a given time (speed)

31. Calculating WORK
Work is equal to the amount of force it takes for an object to move a distance.
Formula: Work = Force X Distance
Work is measure in Joules (Newton/meters)

32. Practice Calculating WORK
How much work does it take to move a box with 50 Newtons of force 10 meters?
Work = Force X Distance
50 X 10 = 500 Joules
Answer Joules

33. Range
Range is the difference between the highest and lowest values in a set of data.
Calculate the range of the following test scores
89, 73, 84, 91, 87, 77, 94
Subtract the lowest score from the highest
94 – 73 = 21
The range of these test scores is 21 points

34. Kinetic vs Potential Energy
Kinetic Energy – Energy of motion
The faster you are travelling the more kinetic energy you have
Potential Energy – Stored energy
The more stored energy you have built up the more potential energy you have

35. Where does the rollercoaster have the greatest kinetic energy?

36. Where does the roller coaster have the greatest potential energy?