Sir Isaac Newton developed his laws of motion in 1665 at the age of 23. The first law, the law of inertia, states that an object at rest stays at rest and an object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force. The second law, the law of acceleration, states that acceleration is produced when a force acts upon a mass, and greater force is needed to accelerate greater masses. The third law, the law of interaction, or action-reaction, states that for every action there is an equal and opposite reaction.

1. The foundation of classical mechanics

2. About Sir Isaac Newton
 He developed his laws of motion in 1665 when he was
at the age of 23

3. First Law: Law of Inertia
 Concerned about bodies at rest or those moving with
constant velocity and assumes that no forces are acting
to change their state.
 It is a belief that everything has a tendency to stop.
 Objects often exhibit inertia if there is a abrupt change
in their state of motion.
 Objects stop because of friction
 Mass is the measurement of inertia
 Objects keep on doing what they’re doing

4. Inertia
 The property of a body to resist a change in its current
state

5. Law of inertia states that...
An object at rest tends to stay at rest, and an object in
motion tends to stay in motion with the same velocity
unless acted upon by an unbalanced force.

6. Examples
 Blood rushes to your feet when inside an elevator that
is going down then stops suddenly.
 Seatbelts keep the passengers on their seats.

7. Second Law: Law of Acceleration

8.  Acceleration is produced when a force acts on a mass.
The greater the mass (of the object being accelerated)
the greater the amount of force needed (to accelerate
the object).

9. Law of Acceleration states that...
The acceleration of an object, as produced by a net force
is directly proportional to the magnitude of the net
force, in the same direction as the net force, and
inversely proportional to the mass of an object.

10. Example

11. Third Law: Law of Interaction
 This means that for every force there is a reaction force
that is equal in size, but opposite in direction. That is
to say that whenever an object pushes another object it
gets pushed back in the opposite direction equally
hard.

12. Example
Let's study how a rocket works to understand
Newton's Third Law.
The rocket's action is to push down on the ground with
the force of its powerful engines, and the reaction is
that the ground pushes the rocket upwards with an
equal force.

13. Law of Interaction states that...
For every action there is an equal and opposite re-action.

14. Quiz
1. A magician pulls a tablecloth out from under dishes and
glasses on a table without disturbing them.
2. A person’s body is thrown outward as a car rounds a curve
on a highway.
3. Rockets are launched into space using jet propulsion where
exhaust accelerates out from the rocket and the rocket
accelerates in an opposite direction.
4. A picture is hanging on a wall and does not move.
5. A person not wearing a seatbelt flies through a car window
when someone slams on the breaks because the person’s
body wants to remain in continuous motion even when
the car stops.

15. 6. Pushing a child on a swing is easier than pushing an
adult on the same swing, because the adult has more
inertia.
7. A soccer ball accelerates more than a bowling ball
when thrown with the same force.
8. A soccer player kicks a ball with their foot and their
toes are left stinging.
9. A student leaves a pencil on a desk and the pencil stays
in the same spot until another student picks it up.
10. Two students are in a baseball game. The first student
hits a ball very hard and it has a greater acceleration
than the second student who bunts the ball lightly.

16. Answers
1. Inertia
2. Inertia
3. Interaction
4. Inertia
5. Inertia
6. Acceleration
7. Acceleration
8. Interaction
9. Inertia
10. Acceleration