1. What is a force? Definition:
SPRING SCALES
Used to measure force
What is a force?
Definition:
a PUSH or PULL that can start, stop or change the direction of an objects motion.

2. What is a force? Measured in _______________ ( ) Answer: Newtons (N)
What are some forces acting on you right now?
Gravity
Air Pressure
Friction

3. Balanced Forces and Unbalanced Forces
Examples
Student vs. Mr. Allen in arm wrestling
BALANCED FORCE!

4. Balanced Forces and Unbalanced Forces
Examples
One student over powering Mr. Allen
UNBALANCED FORCE

5. Balanced Forces and Unbalanced Forces
Examples
3) Mr. Allen pushing on a wall
BALANCED FORCE

6. Balanced Forces and Unbalanced Forces
Examples
4) Mr. Allen pushing on a cardboard box
UNBALANCED FORCE

7. Balanced Forces and Unbalanced Forces
Balanced Forces: Forces that are EQUAL in size but OPPOSITE in direction. NO Motion!

8. Balanced Forces and Unbalanced Forces
Unbalanced Forces: Forces those are UNEQUAL in size. Motion!

9. Friction
Definition:
Force that occurs when 2 substances rub together.

10. 3 Types of Friction SLIDING: friction occurring by sliding motion.
FLUID:
friction occurring through air or liquid.
ROLLING:
friction occurring by rolling motion.

11. Centripetal Force Definition:
a force that pushes or pulls an object into a circular path.
Always directed towards center of the circular path.

12. Examples of Centripetal Force
Swinging car on a piece of rope.
Ferris Wheel, merry-go-round, tilt-a-whirl.
Mr. Allen’s puke story!

13. Newton’s First Law of Motion
Sir Isaac Newton stated, “An object at rest will remain at rest AND an object in motion will remain in motion, until an unbalanced force (gravity, friction, wind resistance) is acted upon it”.
Also known as  INERTIA

14. Examples of Newton’s First Law
1) Pedaling a bike.
Bike will continue to move until an unbalanced force is applied.

15. Examples of Newton’s First Law
2) Sitting motionless in your chair.
Guy will stay motionless until an unbalanced force is acted upon him.

16. Examples of Newton’s First Law
Wearing a seat belt in vehicle.
When secured with seat belt, passengers and driver will stay at rest until an unbalanced force is included (slamming on brakes). Without seat belts, individuals will continue to go forward.

17. Examples of Newton’s First Law
Pulling dollar bill from between two bottles of salad dressing.
Dollar bill will stay in place until an unbalanced force is acted upon it. Like pulling money out from between bottles of salad dressing quickly!

18. Which one would be more difficult to stop? Why?
A bowling ball traveling at 4 m/s.
A ping pong ball traveling at 4 m/s.
Bowling Ball.
Greater Mass!
Greater Momentum!