1. Gravity

2. Newton’s Universal Law of Gravitation

3. Newton’s Universal Law of Gravitation

4. Sample Question 1
Find the gravitational force of attraction between two steel spheres, each of mass 80kg if the distance between their centres is 0.5m

5. Sample Question 2

6. Atmosphere

7. Atmosphere
The force of gravity keeps the Earths atmosphere attached to the Earth.
On the moon the force of gravity is too weak and any gas escapes into space

8. Gravity and Weight

9. Sample Question 3

10. Sample Question 4

11. Sample Question 5
Given that the value of g on the surface of Earth is 9.8 m/s2, at what height above the Earths surface is the acceleration due to gravity equal to half its value on the surface of the Earth?

12. Find the value of the acceleration due to gravity on the Moon, given that the radius of the moon is 1.7 x 106 m and the mass of the moon is 7 x 1022 kg. Hence find the weight of a 60kg woman on the moon.
At what height above the surface of the Earth is acceleration due to gravity equal to one tenth of its value on the surface of the Earth?
The mass of Mercury is 0.04 times the mass of Earth. The radius of Mercury is 0.37 time the radius of Earth. What is the acceleration due to gravity on the surface of Mercury?

13. Newton’s Cannon http://spaceplace.nasa.gov/how-orbits-work/

14. Newton’s Cannon
A + B – velocity is too low, cannonball will fall back to Earth C – velocity is the orbital velocity at that distance from the centre and will continue circling the Earth D – higher velocity than the orbital velocity but not high enough to leave Earth – will have an elliptical orbit. E – velocity is high enough to leave Earth