Newton’s Law of Gravitation

Chapter 7, Section 3

Pg. 263-265

Newton’s Universal Law of GravitationNewton’s Universal Law of Gravitation

EarthMOON

Fg

To keep two moving bodies from shooting off in a straight line, a mutual gravitational force attraction occurs between them.

FEmFmE

The amount of gravitational force that occurs between two masses depends on the distance between the two masses.

Newton’s universal law of gravitation

Fg = (G m1m2 )/r²

G = constant of universal gravitation

G = 6.673 x 10-11 Nm²/kg²

Sample Problem 2Find the distance between a 0.300 kg billiard ball and a 0.400 kg billiard ball if the magnitude of the gravitational force is 8.92 x 10-11 N.

r = ?m1 = 0.300 kg m2 = 0.400 kg

Fg = (G m1m2) /r²Fg = 8.92 x 10-11 N

r² = (G m1m2) / Fg

r = √(G m1m2) / Fg

r = √[6.673 x 10-11 Nm²/kg² (0.4 kg) (0.3kg)]/8.92x10-11 N

r = 3.00 x 10-1 m

G = 6.673 x 10-11 Nm²/kg²