NEWTONS LAWS OF UNIVERSAL GRAVITATION NEWTONS LAW OF

NEWTON’S LAWS OF UNIVERSAL GRAVITATION

NEWTON’S LAW OF UNIVERSAL GRAVITATION Where: Fg = magnitude of the force of gravity (in N) G = 6. 67 X 10 -11 N • m 2/kg 2 M = mass of one object (in kg) m = mass of other object (in kg) r = distance between centres of masses (in m)

WHAT IS GRAVITY? Isaac Newton would say: “A Force of attraction between two objects having mass anywhere in the universe”

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” https: //www. youtube. com/watch? v=jl. TVIMOix 3 I

BIG ‘G’ – 6. 67 X -11 10 2 2 NM /KG What is Gravity? https: //www. youtube. com/watch? v=Efh 4 bu 4 rcbs Read: 1) http: //www. haydenplanetarium. org/tyson/read/2005/09/01/the-importance-of-being-constant 2) http: //www. scientificamerican. com/article/puzzling-measurement-of-big-g-gravitational-constant-ignites-debate-slideshow/ Provide a brief description of how Cavendish measured Big G!

EXAMPLE # 1 A spacecraft with a mass of 3. 00 X 104 kg is 5000 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 106 m. What is the force of gravity acting on the spacecraft?

EXAMPLE # 2 A spaceship has a magnitude of gravitational force of 1. 00 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.

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?

EXAMPLE # 3 Find the distance in terms of r. E, from the surface of Earth, of a 2000 kg spaceship that has a Fg of 970 N.