1. Dec.6, 2017 You need: Clean paper / pencil Warm Up: Mental Math Quiz
I CAN: review and analyze my test score to work toward mastery.

2. FRICTION

3. 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.

4. 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

5. Newton’s 1st Law of Motion
Newton’s 1st law of motion states:
An object at rest will remain at rest,
-and-
an object moving at a constant velocity will continue moving at a constant velocity,
-UNLESS-
it is acted upon by an unbalanced force.

6. Newton’s 1st Law of Motion
What would happen to the things inside the car if the car hit a wall?
That’s because things moving at a constant velocity will stay at a constant velocity unless acted upon by an unbalanced force.
The car was acted upon by an outside force – the force of the wall hitting the car.
The person inside the car wasn’t hit by the force of the wall, so he kept moving at the same speed and in the same direction.
Inside a moving vehicle, everything is moving at the same velocity – your body, the objects in the car, and the car itself.

7. Newton’s 3rd Law of Motion
Newton’s 3rd law says that: For every action force, there is an equal and opposite reaction force.
ALL forces act in PAIRS!
Action Force: Man’s feet push DOWN on the ground.
Reaction Force: Ground pushes UP on the man.

8. Newton’s 1st Law of Motion
BASICALLY…
Newton’s 1st Law of Motion
Objects resist any change to their motion!
This resistance is called INERTIA.
Which one would be easier to push?
or…
That’s because larger objects have more inertia (more resistance to a change in their motion)!

9. Newton’s 2nd Law of Motion
Force = Mass x Acceleration
Mr. Sawyer’s car ran out of gas. How much force does Mr. Sawyer need to push his 750kg car at an acceleration of 1 m/s2?
F = m x a
F = 750 kg x 1 m/s2
F = 750 N right
750 kg
1 m/s2