Newton’s Laws of MotionThe foundation of classical mechanics

About Sir Isaac NewtonHe developed his laws of motion in 1665

when he was at the age of 23

First Law: Law of InertiaConcerned 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 frictionMass is the measurement of inertiaObjects keep on doing what they’re doing

InertiaThe property of a body to resist a change in

its current state

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.

ExamplesBlood rushes to your feet when inside an

elevator that is going down then stops suddenly.

Seatbelts keep the passengers on their seats.

Second Law: Law of Acceleration

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).

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.

Example

Third Law: Law of InteractionThis 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.

ExampleLet'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.

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

re-action.

Quiz1. 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.

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.

Answers1. Inertia2. Inertia3. Interaction4. Inertia5. Inertia6. Acceleration7. Acceleration8. Interaction9. Inertia10.Acceleration