3. Background
Sir Isaac Newton (1643-1727) an English
scientist and mathematician famous for his
discovery of the law of gravity also
discovered the three laws of motion. He
published them in his book Philosophiae
Naturalis Principia Mathematica
(mathematic principles of natural
philosophy) in 1687. Today these laws are
known as Newton’s Laws of Motion and
describe the motion of all objects on the
scale we experience in our everyday lives.
10. Examples of
Newton’s 3rd Law
a)rockets leaving earth
b)guns being fired
c) two cars hit head on
d) astronauts in space
e) pool or billiards
f) jumping out of a boat onto
the dock
g) sprinklers rotating
12. Newton’s Third Law
• Newton’s Third Law of Motion
– When one object exerts a force on a
second object, the second object exerts
an equal but opposite force on the first.
13. Newton’s Third Law
• Action-Reaction Pairs
• The rocket exerts a
downward force on the
exhaust gases.
• The gases exert an equal
but opposite upward force
on the rocket.
FG
FR
14. Newton’s Third Law
For every action there is an equal and
opposite reaction.
