Question

Two identical metal spheres of radius 10 cm are in contact with each other. If density of the metal is 10 g/cc, the gravitational force between the spheres is

Answer 1

Radius of sphere=R= 10cm=0.1m
Volume of sphere=4/3 πr³
=4/3 × 3.14× (10)³
V=4186.6cm³
Mass of sphere=m= Density×Volume
m=10×4186.6
m=41866gm=41.466kg
From Newton's Law of Gravitation,
F=(G.m.m)/r²
Taking all quantities in their SI units
F= [(6.67×10^-11) × 41.47 ×41.47] / (0.1)²
F=11470.8×10^-9
F=1.147×10^-5 N
or
F= 1.147 dyne