Download Sir Isaac Newton’s Three Laws of Motion

Sir Isaac Newton’s
Three Laws of Motion
Newton’s First Law of Motion
“ Every object in a state of uniform motion
tends to remain in that state of motion
unless an external force is applied to it.”
Which Means:
An object in motion tends to stay in
motion, and an object at rest tends to stay
at rest, unless the object is acted upon by
an outside force
Newton’s First Law of Motion
Newton’s first law = inertia
Objects at rest remain at rest.
This means that if a rock is in motion
and nothing at all is pushing on it
or pulling on it, then it will continue
in a straight line forever (or until
something pushes on it).
We usually don’t notice the effects of
Newton’s first law on earth
because the atmosphere and the
air, will eventually slow down any
moving objects.
In space moving objects will obey
Newton’s first law because there
is no air or atmosphere.
A lot of inertia!
Since the train is
so huge, it is
difficult to
move the train
from rest.
Very little inertia.
Since the baby
carriage is so
small, it is very
easy to move
from rest.
Newton’s Second Law of Motion
“The acceleration of an
object is in the same
direction of the externally
applied force and is
directly proportional to the
magnitude of force
applied as well as
inversely proportional to
the mass of the object.”
Which Means:
Acceleration = Force
Mass

Acceleration = the rate at which
velocity changes
 Velocity is measured in meters
per second (m/s)
 Acceleration is usually measured
in meters per second squared
(m/s2)
 Force is expressed in Newtons
(N)
Newton’s Second Law of Motion

The second law governs all acceleration

Acceleration is produced when a force acts on a
mass

The greater the mass (of the object being
accelerated), the greater amount of force needed
(to accelerate the object)
Newton’s Second Law of Motion

Joe makes the 1000kg car accelerate at .05
m/s2
 Using Newton’s 2nd law you can compute how
much force Joe is applying to the car.
Newton’s Second Law of Motion
 Using
the equation: Force = Mass x
Acceleration (1,000 kg x .05 m/ s2)
You would get the answer of 50 N
 Answer:
Joe is applying 50 Newtons of force to
the car.
Newton’s Third Law of Motion
“For every force imposed, there is an equal
and opposing force in reaction, so as the
Earth’s gravity pulls on the Moon, the
Moon pulls back on the Earth with an
equally strong force.”
Which means:
Every action has an equal and opposite reaction (actions = forces)
Newton’s Third Law of Motion

We feel the third law every
time we interact with other
surroundings.

For example when you punch
someone in the face you know
that your hand applies a force
to the person’s face, but the
person’s face also applies a
force to your hand. Usually, the
reason it hurts the face more
than the hand is because the
face is softer than the hand.
Newton’s Third Law of Motion
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