1. BELL RINGER 11/5/14 -GRAB YOU IPAD!
1. James ran 4.2mi from his house to CVS. He then walked back to his house, before going to his grandma's house located .5mi from his house. What is his displacement? What is his distance?
2. What is the speed of a car that has traveled 310mi in 3.95hr?
3. What distance was covered if a car moving at 42m/s travels for 100s?
4. A car accelerates from 20 m/s to 65 m/s in 11.2 seconds. What is the car’s acceleration?
5. In a Distance over Time Graph what does slope measure?

2. Force
CH. 12

3. Forces Force Net Force Push/Pull acting on an object
Causes acceleration
Net Force
Overall force
After combining all forces
end

4. Types of Forces 1) Balanced Forces Forces cancel out Net Force = 0
No change in motion 6N 6N =
Object stays the same
end

5. Types of Forces 2) Unbalanced Forces Forces do NOT cancel
Object accelerates in that direction 6N 3N =
Object will _________
In what direction???

6. Types of Forces 3) Friction Force that opposes an object’s motion
Keeps it still or slows it down
Other Types of Friction:
Static, Sliding, Rolling, Fluid
end

7. Types of Forces Earth’s acceleration due to gravity is 9.8 m/s2
Pulls any 2 objects together
Earth’s acceleration due to gravity is
9.8 m/s2
end

8. Types of Forces 5) Projectile Motion
Falling object that is moving toward the ground.
It ALWAYS has a curved path
end

9. Motion and Forces Isaac Newton Created the “Three Laws of Motion”
Held up for over 300 years
end

10. Motion and Forces Newton’s 1st Law of Motion Inertia
An object at rest will stay at rest, unless acted upon
An object in motion will stay in motion, unless acted upon
Also called the “Law of Inertia”
Inertia
Objects do NOT want to change their motion
end

11. Motion and Forces Newton’s 2nd Law of Motion
An object will accelerate when a force is applied
Weight can also be force of gravity on an object

12. Motion and Forces Practice
A 15.0 kg mass is pulled along by a force of 100 N. What the object’s acceleration?
end

13. Motion and Forces Practice
A 4.5 kg mass is accelerated at 40 m/s2 what is the force that was applied?
If the same force was applied to a 18 kg object, what would be its acceleration?

14. Motion and Forces
A man has a mass of 88 kg. What is his weight on Earth?
If he weighs 141 N on the moon, what is the acceleration due to the moon’s gravity?
end

15. Motion and Forces Practice
A car is accelerated at 30 m/s2 by a force of N. What is the mass of the car?

16. Practice Problems
Force and Acceleration Problems #1, 2, 4, 5 –THINK HARD ABOUT #3

17. Calculating Force with Diagrams
CALCULATE ACCELERATION F= M= A= 6N 3N
12kg

18. Calculating Force with Diagrams
CALCULATE ACCELERATION F= M= A= 6N 3N
8kg 7N

19. Calculating Force with Diagrams
CALCULATE ACCELERATION F= M=
A= 8.5m/s2
20N ?
14N

20. On Own
On your worksheet try the force diagrams 1-6

21. Answers F M A F M A ?
10kg F M A F M A
5kg
3kg F M A ?
7kg F M A

22. 3rd Law of Motion and Momentum

23. Motion and Forces Newton’s 3rd Law of Motion
For every action there is an equal and opposite reaction
DO NOT cancel each other out
ForceA on B = —ForceB on A
The ball pushes back
with -12 N
He is pushing the ball
with 12 N B A
end

24. Momentum Momentum can be defined as "mass in motion." Two components:
_____________ and ______________

25. Formula
Momentum of an object is equal to the mass of the object times the velocity of the object.
Momentum = mass • velocity
p = m • v
The standard metric unit of momentum is the kg•m/s.

26. Momentum Momentum is a Vector quantity.
Meaning:
The direction of the momentum ‘vector’ is the same as the direction of the velocity.
Ex: If a 10 kg•m/s bowling ball is moving westward, then its momentum is in what direction?

27. Variables
An object has a large momentum if either its mass or its velocity is large.
Both variables are of equal importance in determining the momentum of an object.

28. Variable
Objects at rest do not have momentum - they do not have any …….
“mass in motion."

29. Example
Consider a Mack truck and a roller skate moving down the street at the same speed. Which object has a larger momentum?
If the Mack truck was at rest does it still have a larger momentum?

30. Example
A 2250kg pickup truck has a velocity of 25m/s to the east. What is the momentum of the truck?

31. Practice
An ostrich with a mass of 146kg is running to the right with a velocity of 17m/s. Find the momentum of the ostrich.

32. Momentum worksheet
Momentum side of worksheet #1-8

33. Bell Ringer 1. What are Newton's 1st and 2nd of Motion?
2. What is the weight of an object depend on? What are the units?
3. List 3 types of Forces we covered yesterday.
4. What 4 concepts have we learned to calculate using formulas so far for this unit?
5. You have just thrown a 20kg ball 40 meters in 6.5 seconds before it hit the ground and stopped.
a) What is the speed your threw the ball?
b) What is the acceleration rate?
c) What is the Force that you threw the ball?
d) What is the weight of the ball?

34. Force and Momentum Review: ADD TO BELLRINGER

35. BEANIE BABY TOSS

36. Chapter 14: Work and Power
GRAB A BOOK & CALCULATOR
In your notes for this chapter you need to copy down new vocabulary terms:
Work, Power, Horsepower, Joule, Watt, Machine, & Efficiency
You have 10 MINUTES TO COMPLETE THIS

38. Work

39. Work: The Product of the distance the object has moved & the force in the same direction.

40. Work Work NO Movement = NO Work!!!
Movement and Force must be in the same direction
Carrying an Object = NO WORK!!!
end

41. Work
A force of 825 N is needed to push a car. Two students push the car 35 m. How much work is done?
end

42. Work
A hot-air balloon weighs a total of 8000N. If the balloon rises to a height of 1000m how much work was done?

43. Work
A man lifts a 15 N box 1.2 m into the air. How much work did he do?

44. Work
A 10 kg box is pushed 13 m across the floor at an acceleration of 3 m/s2. How much work was done to move the box?

45. Calculation Work Problems 1-5

46. Power
Power
How fast Work is done
Horsepower (hp)
1 hp = 746 watts
end

47. Power
A woman does 3400 J of work over a period of 50 s. How much power did she use?
end

48. Power
A rocket is shot upward with a force of 2 N. It reached an altitude of 1200m in 30 s. How much power was in the rocket?
How much horsepower did the rocket have?

49. Calculation Power 1-5

50. Measuring Power Activity