1. Newton’s Laws of Universal Gravitation

2. Newton’s law of universal gravitation
Where: Fg = magnitude of the force of gravity (in N)
G = 6.67 X N• m2/kg2
M = mass of one object (in kg)
m = mass of other object (in kg)
r = distance between centres of masses (in m)

3. What is gravity? Isaac Newton would say:
“A Force of attraction between two objects having mass anywhere in the universe”

5. What is gravity? Albert Einstein would say:
“Mass curves space-time. This space-time distortion causes objects to fall towards a heavier mass because the heavier mass has resulted to a greater curvature of space-time”

7. Big ‘G’ – 6.67 x Nm2/kg2
What is Gravity?
Read: 1) 2)
Provide a brief description of how Cavendish measured Big G!

8. Example # 1
A spacecraft with a mass of 3.00 X 104 kg is km from the surface of the Earth. The mass of the Earth is 5.98 X 1024 kg and its radius is 6.38 X m. What is the force of gravity acting on the spacecraft?

9. Example # 2
A spaceship has a magnitude of gravitational force of X 102 N on the surface of some planet. If the spaceship moves to a distance of 1.5 times the radius of the planet, from the surface of the planet; determine the magnitude of the gravitational force.

10. Example # 3
A satellite is launched from the surface of Earth. If the satellite loses half of it’s mass on the way into orbit at a radius of 3 times the radius of the Earth. What will the relationship be between force of gravity on Earth and in orbit?

11. Example # 3
Find the distance in terms of rE, from the surface of Earth, of a 2000 kg spaceship that has a Fg of 970 N.