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Newton’s Universal Law of Gravitation. Factors Affecting the Gravitational Force. mass. distance. Mass. m 1. m 2. decrease mass . decreased. force. force varies directly with masses. F g α m 1 m 2. Distance. r. increase r . force. decreased. Force varies inversely with
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Factors Affecting the Gravitational Force mass distance
Mass m1 m2 decrease mass decreased force force varies directly with masses Fgα m1 m2
Distance r increase r force decreased
Force varies inversely with distance squared Fgα 1/r2
Fg α m1m2 Fgα 1/r2 m1 m2 Fg α -------- r2 Fg slope = G m1 m2/r2
G = 6.67 x 10-11 N m2/kg2
A 1000 kg car and a 2000 kg truck are 0.50 m apart. Gravitational force: 5.3 x 10-4 N
Computing mass of Earth radius of Earth: 6.37 x 106 m 1.00 kg mass has a weight of 9.81 N mass of Earth: 5.97 x 1024 kg
2F 4F
¼ F 4F
“g” gravitational field – weight per mass wtg Fg g = ------ = ------ mass m G M = ------ r2 M = planet mass
Effect of changing variables GM g = ----- r2 if M doubles: if r doubles: if M & r doubles: if r becomes ½: 2g ¼ g ½ g 4g
Mars mass: 11% mass of Earth radius: 53% radius of Earth gravitational field for Mars? 0.39 gE = 3.84 N/kg
Net gravitational force on bottom mass? s M M s s M √3 GM2/s2
G m1 m2 Fg = ---------- r2 = weight What would happen to your weight if: Earth had twice mass but the same radius: Twice weight Earth had twice radius but same mass: ¼ weight
What is “g” at top of Mt. Everest (8848 m elevation)? 9.77 N/kg = 9.77 m/s2