1. April 21, 2018 Mental Math…be ready. You need:
Clean paper (2) / pencil
Intro to Forces (back completed)
Warm Up:
Mental Math…be ready.
I CAN: define friction and identify forms of friction.

2. Today’s agenda Mental Math Reminders/calendar
Review speed, magic triangle, acceleration.
Friction notes

3. April 2018 HR 12:10 QUIZ? 1 2 No School 3 4 5 6 7 8 14 15 16 F/M –
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday 1
Easter 2
No School 3 4 5 6 7 8
9 F/M – review, metrics
10 F/M- KE vs. PE
Ramp and marble lab
11 F/M- Bal/un forces
Rope, shoes, magnet
12 F/M-
Friction, mass, gravity
*challenge, quiz
13 F/M- Motion and graphing
Story analysis, create the graph. 14 15
16 F/M –
Graph review
Benchmark
17 F/M/E
18 F/M/E
Graphs
19 F/M/E
Force/friction
20 F/M/E 21 22 23
Forces and energy
Work and Simple machines
QUIZ? 24
Work and simple machines 25
Mech.adv.
HR 12:10 26
Mech. Adv. 27
Mech. Adv 28 29 30
Magnets

4. Swagrrr EOG testing May 2018 1 2 3 Review Test Assess 4 5 6 7 8 9 10
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday 1
Forces and energy
Magnets / eclectricity 2
Catch - up 3
Review
Test Assess 4 5 6 7
Atmosphere 8 9 10 11 12 13
Mother’s Day 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
No School
Memorial Day 29 30 31
Swagrrr
EOG testing

5. June 2018 EOG testing Busch Gardens NCFE testing 1 2 3 4 5 6 7
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday 1
Atmosphere 2 3 4 5 6 7
8 Last day (due to snow) 9
EOG testing
Busch Gardens
NCFE testing

6. How can we describe motion?
REVIEW
How can we describe motion?
Motion can be described by:
DISTANCE (length)
TIME (min, seconds)
SPEED (distance and time)
DIRECTION (which way)
ACCELERATION (change in motion)
Speed up, slow down, change direction
VELOCITY…speed and direction

7. D S T Speed = Distance Time Time = Distance Speed
REVIEW
The magic triangle of magic-ness!!
Speed = Distance
Time
Time = Distance
Speed
Distance = Speed x Time D S T

8. No Motion

9. Constant MOVEMENT
Straight, not curved…
Diagonal, not horizontal…

10. Slow MOVEMENT

11. FAST MOVEMENT

12. FAST vs. SLOW
FAST
SLOW

13. Starting & Stopping

14. Speeding Up
Slowing down

15. Introduction to
FORCES

16. FORCES Forces may WORK TOGETHER or OPPOSE each other.
When 2 or more forces act on an object, the forces combine to form a net force.
Forces may WORK TOGETHER
or OPPOSE each other.

17. FORCES
If the forces cancel each other out, and do not cause the object to move, the forces are said to be BALANCED.
If the forces don’t cancel each other out – 1 force is stronger than the others – the forces are UNBALANCED and will cause a CHANGE IN MOTION.

18. MEASURING FORCE The strength of a force is measured in NEWTONS.
The symbol is (N).
We use a SPRING SCALE to measure force.

19. Shoe lab Now…what if you tried it using a different surface?
Try sand paper (80 grit AND 220 grit), copy paper, foam paper, wax paper.
Hypothesize first!!!

20. Shoe lab
Record the amount of force at the moment the shoe first moves!
Record your data!

21. COMBINING FORCES = 5 N right + 10 N right 5 N right
Two forces in the same direction can add together to produce a larger net force.
5 N
right + =
10 N
right
5 N
right

22. COMBINING FORCES = 5 N right - 5 N left 10 N left
Two forces in opposite directions can subtract to produce a smaller net force in the direction of the larger force.
5 N right - =
5 N left
10 N left

23. COMBINING FORCES 0 N = - 5 N right 5 N left
Two forces may cancel each other out (if equal and opposite) to produce NO NET FORCE.
5 N right
5 N left - =
0 N
(No Net Force)

24. Circle the best answer:
The forces shown above are PUSHING / PULLING forces.
The forces shown above are WORKING TOGETHER / OPPOSITE FORCES.
The forces shown above are EQUAL / NOT EQUAL.
The forces DO / DO NOT balance each other.
The net force is N TO THE RIGHT / N TO THE LEFT / ZERO.
There IS / IS NO motion.

25. Circle the best answer:
7) The forces shown are PULLING / PUSHING forces.
8) The forces shown are WORKING TOGETHER / OPPOSITE FORCES.
9) The forces shown are EQUAL / NOT EQUAL.
10) The forces DO / DO NOT balance each other.
11) The stronger force is pulling RIGHT / LEFT.
12) Motion is the to the RIGHT / LEFT.

26. 50 N
NET FORCE
200 N
150 N
Two movers are trying to move a heavy box. One mover pushes to the right with a force of 150 N. The other mover pushes to the left with a force of 200 N.
a) Draw & label the forces on the diagram.
b) What is the net force? N LEFT
c) Will the box move? YES
d) If yes, in what direction? LEFT

27. 14) Two movers are trying to move a heavy chair
14) Two movers are trying to move a heavy chair. One mover PULLS to the left with a force of 200 N. The other mover PUSHES to the left with a force of 200 N.
a) Draw & label the forces on the diagram.
b) What is the net force?
400 N LEFT
c) Will the chair move?
YES
d) If yes, in what direction?
LEFT
400 N NET FORCE
200 N
200 N

28. MIKE
Four children are fighting over the same toy. Mike is pulling North with a 50 N force, Justin is pulling East with a 40 N force, Chantal is pulling South with a 50 N force, and Tykera is pulling West a 30 N force.
a) Draw & label the forces on the diagram.
b) Is there a net force on the toy?
YES = 10 N EAST
c) In which direction will the toy move?
EAST
d) Who gets the toy?
JUSTIN
50 N
TYKERA
JUSTIN
30 N
40 N
50 N
10 N
Net Force
CHANTAL

29. (Spf – Spi) Acceleration = time D S T Math cheat sheet Formula
Substitution
Final answer with unit!

30. FRICTION

31. The force that slows the ball to a stop is FRICTION.
What will happen when the ball is released?
When the ball reaches the bottom of the slope, will it keep moving forever?
The force that slows the ball to a stop is FRICTION.
Since the ball stops, there must be a force acting to slow the ball down.

32. What is Friction?
Friction is a force that two surfaces exert on each other when they rub against each other.
The direction of the friction force is always OPPOSITE to the direction of the motion.
Direction of Motion
Friction Force

33. Direction of Intended Movement
Types of Friction
Static Friction opposes the motion of an object that is at rest
To make the object move, you have to exert a force larger than the force of static friction.
Direction of Intended Movement
Static Friction Force

34. Sliding Friction Force
Types of Friction
Sliding friction occurs when two solids slide over each other.
Sliding friction makes car brakes work and stops athletes from slipping.
Direction of Slide
Sliding Friction Force

35. Types of Friction
Rolling friction occurs when an object rolls across a surface.
Rolling friction is easier to overcome than sliding friction for the same materials.
Direction of Motion
Friction Force

36. Types of Friction
Fluid friction occurs when a solid object moves through a liquid or gas.
Air resistance is a type of fluid friction.
Direction of Motion
Friction Force

37. Which type of friction is slowing down the object in each situation?
You are slipping down a waterslide at Emerald Pointe.
You use a lot of force to slide a desk across the floor.
You’re riding a skateboard down the street and it slowly rolls to a stop.
You try to push the couch, but can’t seem to move it.
FLUID FRICTION
SLIDING FRICTION
ROLLING FRICTION
STATIC FRICTION

38. Friction Thought Questions
Why would you add oil to a rusty bike chain?
Why would you add sand to an icy driveway or road?
Why is it easier to move heavy furniture using a handcart rather than pushing it?
Why would a shoe company be interested in studying friction?
What would happen if we repeated the tug-of-war and one team had only socks on?

39. Review of Friction Forces

40. Review - What is Friction?
Friction is a force that two surfaces exert on each other when they rub against each other.
The direction of the friction force is always OPPOSITE to the direction of the motion.
It SLOWS down moving objects!
Direction of Motion
Friction Force

41. Conclusions Questions
Which surface material created the MOST frictional force?
Which surface material created the LEAST frictional force?
Give an example of a situation where we use a certain surface material to:
a) REDUCE friction
b) INCREASE friction

42. & AIR RESISTANCE The physics of falling
GRAVITY
& AIR RESISTANCE
The physics of falling

43. The Force of Gravity
Gravity is the force that pulls all objects down to the earth.
Rain falls from the sky down to earth…
If you drop a book, it falls to the ground…
If you trip, you’ll fall down…

44. Universal Gravitation
Actually in science, gravity is a force of attraction that acts between ALL objects (the earth, you, the desk, a book)
The force of gravity is much STRONGER for LARGER objects (more mass).

45. Universal Gravitation
Because the Earth is by far, the largest and closest object around, it has the greatest force of attraction...
So, no matter where you are on earth, all things fall to the ground due to gravity…

46. What is “free fall”?
When gravity is the ONLY force acting on an object, it is in free fall.
In that case, gravity is an UNBALANCED FORCE which causes the object to accelerate.

47. Acceleration due to Gravity
Calculate the acceleration of an object in free fall.
A = Final speed – initial speed
time
A = 50 m/s – 0 m/s
5 s
Acceleration = 10 m/s2

48. Objects in Free Fall Do all objects fall at the same rate?
If we dropped a bowling ball and a tennis ball from the same height, which would land first?

49. Question: How does mass affect the speed of a falling object?
Mass and Gravity
Nov. 15, 2017
Question: How does mass affect the speed of a falling object?
Hypothesis: (What do you think will happen AND WHY?)
Observations & Data Collection:
Repeat each trial twice and record your observations.
Ping pong ball vs. Wooden ball:
Wooden ball vs. Metal ball:
Ping pong ball vs. Metal ball:
Conclusion: (One sentence)

50. Objects in Free Fall Do all objects fall at the same rate?
ALL objects in free fall travel at the same rate, regardless of mass!
In free fall, heavy objects and light objects fall at the same rate!

51. So, which will land first?
WHY does the penny land first?
Remember the force that opposes motion (slows things down)? FRICTION!
Falling objects experience friction with the air called AIR RESISTANCE that slows them down.

52. Air Resistance
The larger the object (more surface area), the more air resistance.
That’s why parachutes work! The upward force of the air acting on the LARGE parachute slows you down as you fall.

53. Air Resistance Draw a diagram showing the forces…
Gravity
Draw a diagram showing the forces…
Downward force of gravity is same on both.
Upward force of air resistance is greater on the feather.
The net force (down) is greater on the penny.
Net Force on Penny
Net Force on Feather

54. Without air resistance, all objects would fall at the same rate…
Galileo Drops the Ball
Hammer and Feather Drop on the Moon

55. That’s why astronauts weigh less on the moon!
Gravity on the moon?
The force of gravity is much weaker on the moon because…
It is much farther away from earth.
The moon is much smaller than earth.
That’s why astronauts weigh less on the moon!

56. Gravity Review
Gravity is the force that pulls all objects down to the earth.
When gravity is the ONLY force acting, ALL objects accelerate at a rate of 10 m/s2.
Mass doesn’t matter – in free fall, heavy objects and light objects fall at the same rate!

57. Air Resistance Review
Some objects take longer to fall – they are slowed down by FRICTION with the air called AIR RESISTANCE.
The larger the surface area, the greater the force of air resistance pushing up.
Without air resistance, all objects would fall at the same rate…

58. Draw a free body diagram of the sky diver and label ALL the forces.
Gravity = 1000 N
Air Resistance = 800 N
What is the net force?
Air Resistance = 800 N
Net Force = 200 N
Gravity = 1000 N