1. Gravity Equation F = force of gravity G = gravitational constant (6*10 -11 ) 0.00000000006 M 1 = mass of body 1 M 2 = mass of body 2 S 2 = distance between M 1 & M 2 squared F = M 1 * M 2 S2S2 G Web

2. Gravity 1. The force of gravity is not effected by other bodies present. 2. The force of gravity is equal but oppositely directed. F=ma Newton’s second law F = M 1 * M 2 S2S2 G

3. Gravity F = M 1 *M 2 S2S2 M1A1M1A1 M2A2M2A2 M 1 A 1 = M 2 A 2 M 2 is larger than M 1 so, A 1 must be larger than A 2 if they are equal. If the force is equal and opposite, then: = [Across a crowded room, you and an airplane] G F M2M2 M1M1 F = MA for both Web

4. Gravitational Constant G ~ 6*10 -11 - a very small number 0.00000000006 What is the attraction between you and the person next to you? What is the attraction between you and the earth? F = M 1 * M 2 S2S2 G

5. Gravity F = M 1 *M 2 S2S2 G If masses stay the same, but the distance increases, how does the force of gravity change? M same S increases =F <

6. Gravity F = M 1 *M 2 S2S2 G If distance stays the same, but the masses increase, how does the force of gravity change? increase same =F >

7. Gravity Will a body always have the same mass if the volume remains constant? NO Same volume (size) Density may be different, so masses are different Venus (0.95 radius of earth, density 0.53)

8. Acceleration due to Gravity (g) The acceleration of a body arising from the earth’s gravitational pull. Units are ft/sec 2 or m/sec 2 At the earth’s surface g is: 9.8 m/sec 2 or 32 ft/sec 2 (g) depends on position Web

9. Acceleration due to Gravity (g) A body falling will continue to accelerate until air friction causes the body to reach a terminal velocity. Acceleration due to gravity is independent of mass F = M A

10. The Beam Balance and Weight Gravity Known massunknown mass 1 kg? Weight = pull of gravity (a force) [ Will it work everywhere? on Earth, another planet? in space? ]

11. Weight Weight is the force of gravity between me and the earth. 1. How can I reduce my weight? A) move scales to second floor? B) move to the mountains? F = M 1 *M 2 S2S2 G

12. Gravity and the Earth F = M 1 *M 2 S2S2 G N S N S -Rotates west to east -Velocity greater at equator, zero at poles -Centrifugal force bulges earth at the equator -So, the earth is slightly squashed at equator -equator diameter is 42 km > than pole diameter diameter Web