#### Transcript Gravity

```Gravity
The force of attraction between
objects that is due to their masses

All matter has mass, so all matter experiences
gravity.
The Law of Universal Gravitation


Stated by Sir Isaac Newton (1642-1727)
“All objects in the universe attract each other
through gravitational force . The size of the
force depends on the masses of the objects and
the distance between them.”
Mass vs. Weight

Mass is the amount of matter in an object.
(Measured in grams or kilograms)


Weight is the measure of the gravitational
force exerted on an object.
(Measured in Newtons)
Why do we weight less on the moon?
-Because the moon has less mass than the
earth.
How many Newtons do you weigh?

1. Convert lbs. to kg
(Weight in pounds X 0.4536)
2. Convert kg to Newtons
(Weight in kg X 9.8)
Ex. 190 lbs X 0.4536 = 86.18 kg
86.18 kg X 9.8 = 844.60 N
Acceleration due to gravity

9.8 m/s/s – the rate at which all objects fall
towards earth (ignoring air resistance.)
Terminal Velocity

Is the point at which a falling object stops
accelerating and begins to fall at a constant
speed.

If there were no atmosphere there would be no
air resistance. (That’s why a feather and a rock
would land at the same time if dropped on the
moon.)
```