Transcript Gravity

The force of attraction between
objects that is due to their masses
All matter has mass, so all matter experiences
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
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
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