Summary Grade 12 IEB Physical Sciences - Newton's Law of Universal Gravitation (Physics Section D)

Newton's Law of Universal Gravitation
Every particle with mass in the universe attracts every other particle with a force which is
directly proportional to the product of their masses and inversely proportional to the square of
the distance between their centres.
𝑚1 𝑚2
F=G
𝑟2

Fg

m1 m2
Fg


r


m1 - Mass of object 1
m2 - Mass of object 2
r - Distance between their centres
G - 6.7 x 10-11 N.m2.kg-2

Fg m1.m2
ɣ




1
Fg
ɣ




𝑟2

Fg

Gradient = G




𝑚1 𝑚2
𝑟2


Weight (Fg)
The gravitational force the Earth exerts on any object on or near its surface.
𝑚 𝑚
F = G 𝑟1 2 2 or Fg = m x g
Unit: Netwons, N



Mass
A measure of the amount of matter that an object is composed of.
Unit: Kilograms, kg