1. And other weird, wild stuff.
Fc and Fg
And other weird, wild stuff.

2. Circular Motion Uniform Circular Motion
Movement of an object around a fixed radius
Also at a fixed speed.
Does an object going around in a circle accelerate?
YES!
It changes direction constantly!

3. B. Direction is important
If the object is going in a circle, what direction does the acceleration go? R Ac
P.S.
Ac and Vc
are at 90° r Vc
TOWARDS THE CENTER! ALWAYS, ALWAYS, ALWAYS!

4. C. FORMULAS Vc = 2πr Vc is called centripetal velocity ac = vc2 r
ac is called centripetal acceleration

5. II. Centripetal Force
According to Newton’s 2nd Law
F= ma
So, Fc = mac
Or, Fc = mvc2 r
Centripetal Force ALWAYS goes toward the center due to Newton’s 2nd Law.

6. III. Centrifugal Force A “fake” force.
You are in a ride that goes in a circle. You feel like you are pushing against your seat.
You are not
It is your intertia……it is not a force

7. IV. Law of Gravitation Bob Newton Came up with it.
The myth was he was hit in the head with an apple.
Didn’t use an apple, used the moon.
The moon is falling to Earth due to gravity
The Earth is being pulled to the moon with the same gravity
Why?
NEWTON’S 3rd Law
Newton found out that the gravity is dependent upon the mass of the two objects and the distance between them.

8. B. FORMULA Fg = Gm1m2 r2 m1 and m2 are the masses of the two objects
By the way, This equation works anywhere in the universe.
Fg = Gm1m2 r2
m1 and m2 are the masses of the two objects
r is the distance between the centers of the two objects.
G= gravitational constant = 6.67 x 10-11

9. C. Example
What is the force of gravity (weight) of a 10 kg dog on Earth? (I would like you to do this 2 different ways.)
You are going to need the following info:
g = 9.8 m/s2
Mass of Earth = 5.97 x kg
Radius of earth = m