Newton's Laws Of Motion 3v4q32

NEWTON’S LAWS OF MOTION

Early Ideas on FORCE & MOTION • Aristotle - Believed that a continuous application of force on a body is required to produce and maintain the motion of the body - The absence of an external force, a moving body will stop

Once you stop pulling the chair, it will stay at rest.

Objects continue to move though the force that started the motion of the body is removed

• Galileo - He disproved the theories made by Aristotle - He made an experiments on an inclined plane & through logical thinking

Ball rolling down and up inclined planes E D

A

h

C

• Galileo said that the smaller the inclination of the plane in relation to the horizontal, the farther the ball will have to roll to reach the same height. • He concluded that the smaller the angle of inclination from the horizontal the less is the deceleration of the ball. He reasoned that if that is the case, the deceleration becomes zero when the angle of inclination is zero.

• Galileo with his logical mind concluded that a moving body along a horizontal frictionless surface does not require a continuous application of force to maintain its uniform velocity.

ISAAC NEWTON • Sir Isaac Newton was one of the greatest scientists and mathematicians that ever lived. He was born in England on December 25, 1643. He was born the same year that Galileo died. He lived for 85 years.

• He was interested in experimental science thus his studies restated the idea of Galileo and came up with the Law of Inertia

First Law : LAW OF INERTIA • INERTIA - A property of a body to resist changes in its motion - It is equal to the mass of the body

LAW OF INERTIA • An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

What does this mean? • This means that there is a natural tendency of objects to keep on doing what they're doing. All objects resist changes in their state of motion. In the absence of an unbalanced force, an object in motion will maintain this state of motion.

This law is the same reason why you should always wear your seatbelt.

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).

What does this mean? • Everyone unconsciously knows the Second Law. Everyone knows that heavier objects require more force to move the same distance as lighter objects.

• However, the Second Law gives us an exact relationship between force, mass, and acceleration. It can be expressed as a mathematical equation:

example of how Newton's Second Law works

• Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.05 m/s/s. Using Newton's Second Law, you can compute how much force Mike is applying to the car.

Third Law: LAW OF ACTION AND REACTION •For every action there is an equal and opposite re-action.

What does this mean? • 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.

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.

Pushes the rocket upward by the ground with equal force

The rocket is pushing the ground

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