This document summarizes Newton's three laws of motion. It explains that the first law states that an object at rest stays at rest and an object in motion stays in motion unless acted on by an unbalanced force. The second law states that force equals mass times acceleration. The third law states that for every action there is an equal and opposite reaction. It provides examples to illustrate each law, such as how inertia causes unrestrained passengers in a stopped car to continue moving forward, and how rockets are propelled upward by the equal and opposite reaction of exhaust gases pushing downward.

1. Newton’s
Laws of Motion
Naveed Malik
7042
11th - Class

2. Newton’s Laws of Motion
1st Law– An object at rest will stay at
rest, and an object in motion will stay
in motion at constant velocity, unless
acted upon by an unbalanced force.
2nd Law– Force equals mass times
acceleration.
3rd Law– For every action there is an
equal and opposite reaction.

3. Newton’s First Laws of
Motion
Basically, an object will “keep doing
what it was doing” unless acted on by
an unbalanced force.
If the object was sitting still, it will
remain stationary. If it was moving at a
constant velocity, it will keep moving.
An object at rest tends to stay at rest
and an object in motion tends to stay in
motion unless acted upon by an
unbalanced force.
It takes force to change the motion of
an object.

4.  Inertia is the tendency of an object to resist
changes in its velocity: whether in motion or
motionless.
 An object at rest tends to stay at rest and an
object in motion tends to stay in motion unless
acted upon by an unbalanced force.
 It takes force to change the motion of an object.
1st Law

5. What is this unbalanced force that acts on an object in
motion?
• There are four main types of friction:
– Sliding friction: ice skating
– Rolling friction: bowling
– Fluid friction (air or liquid): air or water resistance
– Static friction: initial friction when moving an object

6. Don’t let this be you. Wear seat belts.
Because of inertia, objects (including you) resist changes
in their motion. When the car going 80 km/hour is
stopped by the brick wall, your body keeps moving at 80
m/hour.

7. Two teams are playing tug of war. They are both
exerting equal force on the rope in opposite
directions. This balanced force results in no change
of motion.

8. Newton’s Second Law Of
Motion.
The net force of an object is equal to
the product of its mass and
acceleration, or F=ma.
When mass is in kilograms and
acceleration is in m/s/s, the unit of
force is in Newton (N).
One Newton is equal to the force
required to accelerate one kilogram of
mass one meter/second/second.
Force is directly proportional to mass and
acceleration. Imagine a ball of a certain
mass moving at a certain acceleration.
This ball has a certain force.

9. Newton’s 2nd Law proves that different masses accelerate to the
earth at the same rate, but with different forces.
• We know that objects with
different masses accelerate to
the ground at the same rate.
• However, because of the 2nd
Law we know that they don’t
hit the ground with the same
force.
F = ma
98 N = 10 kg x 9.8 m/s/s
F = ma
9.8 N = 1 kg x 9.8 m/s/s

10. What does F = ma say?
F = ma basically means that the force of an object comes from its
mass and its acceleration.
Something very small (low mass) that’s changing
speed very quickly (high acceleration), like a bullet,
can still have a great force. Something very small
changing speed very slowly will have a very weak
force.
Something very massive (high mass) that’s
changing speed very slowly (low acceleration), like
a glacier, can still have great force.

11. Newton’s Third Law Of
Motion.
For every action there
is an equal and
opposite reaction.

12. Law in Nature
• Consider the propulsion of a fish
through the water. A fish uses its
fins to push water backwards. In
turn, the water reacts by pushing
the fish forwards, propelling the fish
through the water.
• The size of the force on the water
equals the size of the force on the
fish; the direction of the force on
the water (backwards) is opposite
the direction of the force on the fish
(forwards).

13. Think about it . . .
What happens if you are standing on a skateboard or a slippery
floor and push against a wall? You slide in the opposite
direction (away from the wall), because you pushed on the wall
but the wall pushed back on you with equal and opposite force.
Why does it hurt so much when you stub your toe? When
your toe exerts a force on a rock, the rock exerts an equal
force back on your toe. The harder you hit your toe against
it, the more force the rock exerts back on your toe (and the
more your toe hurts).

14. Example of Newton’s Third Law
• The baseball forces the bat to
the left (an action); the bat
forces the ball to the right (the
reaction).
•The reaction of a rocket is an application of the
third law of motion. Various fuels are burned in
the engine, producing hot gases.
The hot gases push against the inside tube of
the rocket and escape out the bottom of the
tube. As the gases move downward, the rocket
moves in the opposite direction.

15. Thank You
Naveed Malik
7042
11th - Class