1. All things with are affected by .
GRAVITY
All things with are affected by
Two objects, whether large or small, always have a gravitational force between them.
Gravitational force as mass
Gravitational force as distance

2. Gravity & Projectile Motion
FREE FALL: the motion of a body when _______ the force of ____________________ is acting on the body.
Freefall acceleration near Earth’s surface is ____________________
If we disregard air resistance, all objects near Earth accelerate down (fall) at _____________________, abbreviated g.
Because acceleration is proportional to Force/mass, sometimes we say,
g= 9.81 N/kg
When there is no air resistance (only gravity), a mouse and an elephant will fall _________________________=9.81m/s2

3. Gravity & Projectile Motion
Free Fall Check
Is a skydiver in free fall? Why?
If a feather and a billy goat are dropped from the same height near Earth’s surface, which will reach the ground first if we disregard air resistance? Why?

4. Gravity & Projectile Motion
Weight is different from mass.
MASS: a measure of the _________________________________ _____________________________ in an object.
Measured in kilograms (kg)
WEIGHT: the _______________________________an object experiences because of its mass.
Measured in newtons (N) or pounds (lb)
Equal to mass times free-fall acceleration.
weight = mass x free-fall acceleration
(Fg = mg)
force = mass x acceleration
(F=ma)
Mass = .25 kg
g = 9.81m/s2
weight = mg =

5. Gravity & Projectile Motion
What happens when things fall?
An object’s falling ___________________________ is constant when air resistance ___________________________ weight.
Balanced forces means constant velocity (no acceleration)…
TERMINAL VELOCITY: The constant velocity of a falling object when the force of ___________________________ is equal in magnitude and opposite in direction to the ___________________________
This is the point of parachutes!
Increase air resistance

6. Gravity & Projectile Motion
Weight Check
Gravity & Projectile Motion
Do you have the same mass on the moon? Why?
Do you have the same weight on the moon? Why?

7. Gravity & Projectile Motion
Orbiting objects are in _______________________
The moon stays in orbit around Earth because Earth’s gravitational force ___________________________ on the moon.
Two motions ___________________________ to cause orbiting.
Forward motion and downward motion to Earth
CENTRIPETAL FORCE: Force that causes objects to travel in a curved or circular path

8. What’s your weight/mass/Force
1 pound = kilograms
1 pound = Newtons
Take your weight in pounds = (I’ll use 100…. You can pick any number to try this with)
First convert your weight to kilograms (mass)
…….. x = 100 lbs x = kg
Then take your mass in kg x g (9.81 m/s2) to get Fg (N)
……… x 9.81 m/s2 = x 9.81 = N
Last, take your force and convert back to lbs to check…
/ = / = 100 pounds!