1. Forces
On a post-it, write down anything you know about the word force or the different ways you use the word force.

2. Scientific Definition
A force is a push or a pull of an object.
When there is a force, one object is applying a force and on object is receiving the force.

3. Characteristics Used to Describe a Force
Magnitude (size)- the amount of force being exerted
Direction- the direction in which the force is moving the object

4. Effects of a Force on An Object
MOTION! -start moving -stop moving -speed up -slow down -change directions

5. Identifying Forces
Some forces are obvious, because you see where the force is coming from since they act based on touch.
Some forces are not obvious because they can act with out touch.
GRAVITY
MAGENTS
-STATIC

6. Measuring a Force
The unit used to measure how much force an object is exerting is the Newton.
The abbreviation for Newton is N.
One Newton can lift one small apple.
The tool used to measure force is a spring scale.
The more mass an object has, the
more force it will require to move
the object.
As mass increases, force increases.

7. Combining Forces
Sometimes there is more than one force being exerted on an object
The forces being exerted may be working in the same direction.
Example: a plane traveling in the same direction as the wind
Sometimes there are multiple forces acting on an object in different directions.
Example: a plane flying against the wind

8. Think, Pair, Share: Name all the forces acting on the kite
Think, Pair, Share: Name all the forces acting on the kite. Are all the forces working in the same direction?

9. Net Force
Net force is the combination of all the measure of all the forces being exerted on an object.
In order to determine the net force when the forces are acting in the same direction, you add up the measure of all the forces.
Example: My sister and I are moving a piano together in the same direction. I exerted 15 Newtons while my sister exerted 10 Newtons. What is the net force applied to the piano?
______ N to the ___________ (direction)

10. Net Force: Different Directions
To determine the net force on an object with forces acting in different directions, you subtract the smaller force from the bigger force.
When there are forces working in different directions, it will lessen the force on the object.

11. Net Force

12. What does net force tell us?
if the object will move
in which direction the object will move
how strong the force is on the object

13. Balanced Forces
A balanced force is produced when two forces are acting in different directions and are equal, which means the net force is 0.
When the forces applied to an object produce a net force of zero, the forces are balanced.
Balanced forces don’t cause movement in an object.
Balanced forces will not change the motion of a moving object.

14. Unbalanced Force
When the force of an object is not zero, then it is an unbalanced force.
An unbalanced force is when one force is stronger than another force.
An unbalanced force causes a change in the movement of an object.
start/stop movement
change direction of movement
speed up/ slow down movement

15. Picture Walk
Choose a picture with your group. Then discuss and answer the following questions on an index card. Be ready to present the information to the class.
What are the forces being exerted on the object?
Are the forces balanced or unbalanced?
What are the effects of the force?
How would you determine the net force being exerted on the object?

16. Friction
Question: When you kick a soccer ball, eventually it will stop moving. Why?

17. Description of Friction
Friction is a force that appears whenever two things rub against each other.
Friction always works in the opposite direction of the force being exerted on the object. Therefore, it affects it slows down its movement and eventually causes the object to stop moving.
Example: force of kick causes ball to move in one direction, while friction is slowing down the movement of the ball and eventually slowing it down.
Even though a surface may seem smooth, it actually has tiny bumps that can be seen with a microscope. Therefore all surfaces cause friction.

18. Friction Depends On:
mass: objects that have more mass push harder and closer against the surface and therefore cause more friction.
surface: Objects with smooth surfaces cause less friction. Objects with rough, bumpy surfaces cause more friction.

19. Exit Ticket
What do you think would happen if you kick a ball in space? Why?
How does friction affect the force exerted on an object?

20. Four Types of Friction
1) rolling friction- when one object ROLLS over another object, usually on wheels
Examples: bike, car, stroller, ball , train, rollerblading, skateboarding
2) sliding friction- friction used when one surface slides past another surface
Examples: writing, walking, itching your skin,
pushing a book, touching something
Which of he two produce more friction?
(think of a suitcase)

21. 3) fluid friction- any friction that occurs between a liquid or a gas and an object
Examples: objects in water, objects in air
4) Static friction- the friction that occurs between two objects when object applies a force on another object but the object does not move. Static friction disappears once the object begins to move.
Example: when you push something heavy but it does not move, static friction occurs. Once it moves, static friction disappears and sliding friction occurs.

22. Is friction a good thing or a bad thing?
positive effects
friction between floor and feet helps us walk
car brakes, tires pushing against the floor to move
holding anything in your hand would be difficult without friction- writing
sports- cleats for softball, gloves for better grip, sneakers
negative effects
car parts rub together causing engine parts to heat up and be worn down
holes in socks, clothing, shoes worn out from friction
friction by water and wind causes erosion/rust –bike in rain

23. Increasing/Decreasing Friction
adding wheels
adding liquids
lubricant-oil, wax, grease, air
making the surface smoother (sandpaper)
increasing friction:
make surfaces more rough (brillo, salt, gloves)
add mass

24. Exit Ticket
Based on what we learned today, explain why a ballerina wears ballet slippers.
Why is friction good for a car? Bad for a car?

25. What do you already know about gravity?
Record what you know about gravity on a post it. Then post it onto the board.

26. What is gravity? Gravity is a force of attraction between two objects.
All objects with mass have a gravitational force. The gravitational force pulls objects towards each other.
The force of gravity can affect the motion of an object by changing its speed, direction or both.

27. Gravity depends on:
mass- the more mass an object has, the more gravitational force it will have. (Example: you and the desk vs. you and Earth.)
2) Distance- the closer two objects are to one another, the greater the gravitational force.

28. Isaac Newton
British scientist named Isaac Newton realized while watching an apple fall from the tree that there has to be some unbalanced force that is causing the apple to move.
He came to the conclusion that the force was gravity which is pulling everything on Earth towards Earth.
This became known as the law of universal gravitation- it is a law because it applies to all things in the universe.

29. Effects What are some effects of gravity on you?
What would happen without gravity?

30. Review: What is the difference between weight and mass?
Mass- the measure of how much matter is in an object
weight-the measure of gravitational force on an object
Mass never changes, but weight changes depending on how much gravitational force there is on the object.
You weigh less on the moon than you do on Earth-why?
Why is there less gravity on the moon?

31. Directions You will get into groups of 4 and choose roles.
pens/pencils keeper
teacher getter
clarifier
coordinator /point keeper
You will discuss the answers to each of the questions based on what you learned about gravity. While you discuss, all pens/pencils must be placed in the bin.
After you discuss the answers, each student will write down the answer to the question on a post-it and place it underneath the question they answered.
If one person has a question, then all students must put their pens/pencils down to discuss and answer the question.
Reminders:
Do now write any of the answers in your notes
When there is talking there is no writing When there is writing there is no talking.

32. Use the picture to help answer the questions.

33. How does gravity affect the tides?
The side of the Earth that is facing the mood has a high tide and the opposite side has a high tide because graity is pulling the water tiwards the moon.
The sides that are not facing the moon are expeiencing low tide. Th