1. Gravity and Weight Worksheet (#23)
Agenda 4/13/10
Go over homework assignment (#18).
Newton’s Law of Universal Gravitation (#19)
Start homework.
Homework:
Gravity and Weight Worksheet (#23)

2. Homework Assignment (#18)
8.0 m/s2
3.4 m/s2
-5.8 m/s2
30.0 m/s2
6.8 km/hr2
6a. An object in motion will remain in motion and an object at rest will remain at rest unless acted upon by an unbalanced force.
6b. Remains in current location unless acted upon by an outside force.
A force. Friction stops or slows down an objects motion.

3. Homework Assignment (#18)
Situation
Sliding Friction
Fluid Friction
Rolling Friction
8. A swimmer in a pool
9. A child on a playground
slide
10. A skydiver in the air
11. A skydiver landing
12. Rubbing hands together
13. An airplane taxiing on
a runway
14. A flying airplane X X X X X X X X

4. Newton’s Law of Universal Gravitation
A. Newton determined that any two masses exert a gravitational force on each other.
B. The ___________________ the 2 masses, the ___________________ the force will be.
C. The ___________________ the objects are the ___________________ gravitational force will have.
LARGER
GREATER
CLOSER
GREATER

5. Gravitational Formula
Gravity (g) = Mass (m1) X Mass (m2)
distance (d2)
Units: g =
m1 =
m2 =
d =
GRAVITATIONAL FORCE (Newtons – N)
MASS OF OBJECT #1 (Kilograms – kg)
MASS OF OBJECT #2 (Kilograms – kg)
DISTANCE BETWEEN TWO OBJECTS (Meters – m)

6. Weight
A. Definition: the measure of the gravitational force on an object.
B. When you stand on a scale to weigh yourself, you are actually measuring the amount of gravitational force pulling on you. C. D.
Your mass does not change when you go to the moon but your weight decreases because there is less gravity on the moon.
Weight is a FORCE.
Mass is a measure of the amount of matter an object contains.

7. weight (w) = mass (m) X gravity (g)
Weight Formula
weight (w) = mass (m) X gravity (g)
Units: w =
m =
g =
WEIGHT (Newtons – N)
MASS (Kilograms – kg)
ACCELERATION DUE TO GRAVITY (M/S2)

8. Acceleration due to Gravity
If an object is falling (on Earth) its:
acceleration due to gravity = ________
All objects near the surface of the Earth fall with the same rate of acceleration ___________________________
9.8 m/s2
9.8 m/s2

9. Acceleration due to Gravity
B. If an object is falling (on Moon) its:
acceleration due to gravity = ________
All objects near the surface of the Moon fall with the same rate of acceleration ___________________________
1.6 m/s2
1.6 m/s2

10. Example
Example: a feather and bowling ball will fall with the same rate of acceleration on Earth __________________________.
However,_________________________________________________________
___________________________
9.8 m/s2
A BOWLING BALL WILL HIT THE GROUND FIRST
BECAUSE IT HAS MORE MASS THAN THE FEATHER. THEREFORE,
THE BOWLINGBALL HAS A GREATER VELOCITY.

11. Example
The feather is going to take longer to fall than the bowling ball since the feather will be affected more by _________________________. If there was no __________________________, the feather and the bowling ball would reach the ground at the same time if they were released at the same height at the same time.
AIR RESISTANCE
AIR RESISTANCE