Bridge Course Activity

Group 1

1

Newton’s Laws Of M tion

2

About Sir Isaac Newtono Sir Isaac Newton was one of the greatest scientists and mathematicians that ever lived.

o He was born in England on December 25, 1643

o While Newton was in college he was writing his ideas in a journal. Newton had new ideas about motion, which he called his three laws of motion.

He also had ideas about gravity, the diffraction of light, and forces.

3

Laws Of Motion

o Newton’s 1st Law Of Motion (The Law of Inertia)

o Newton’s 2nd Law Of Motion (Law of Force and Acceleration)

o Newton’s 3rd Law Of Motion

4

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.This law is called "the law of inertia".

Newton’s 1st Law Of Motion

5

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. Let's study the "skater" to understand this a little better

6

The first law can be stated mathematically when the mass is a non-zero constant as,

Consequently,

An object that is at rest will stay at rest unless a force acts upon it.

An object that is in motion will not change its velocity unless a force acts upon it.

7

Examples of newtons first law of Motion

(1) Why use seat belts? Riding in a car you and the car have the same motion. When the brakes are applied, the brakes stop the car. What stops you? Eventually the steering wheel, the dashboard, or the window unless they are replaced by a seat belt, which stops your body.

(2) While you are riding in the front passenger seat of a car, the driver suddenly turns left. What about you? You continue to move in a straight line until the door to your right, turning left, eventually runs into you. In the car it may appear to you that you slid outward and hit the door.

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).

Newton’s 2nd Law Of Motion

10

What does this mean?

The second law states that the rate of change of momentum of a body, is directly

proportional to the force applied and this change in momentum takes place in the

direction of the applied force.However, the Second Law gives us an exact relationship between force, mass, and

acceleration. It can be expressed as a mathematical equation:

FORCE = MASS times ACCELERATION Or

11

The second law can also be stated in terms of an object's acceleration. Since Newton's second law is only valid for constant-mass systems, mass can be taken outside the differentiation

operator by the constant factor rule in differentiation. Thus,

where F is the net force applied, m is the mass of the body, and a is the body's acceleration. Thus, the net force applied to a body produces a proportional acceleration. In other words, if a body is

accelerating, then there is a force on it

12

This is an 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.

Answer = 50 newtons13

For every action there is an equal and opposite re-action

Newton’s 3rd Law Of Motion

15

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.

16

The third law states that all forces between two objects exist in equal magnitude and opposite direction: if one object A exerts a force FA on a

second object B, then B simultaneously exerts a force FB on A, and the two forces are equal and

opposite:

FA = −FB

17

When a bullet is fired from a gun with a certain force (action), there is an equal and opposite force exerted on the gun in the backward direction (reaction).

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.

Examples of newtons Third law of motion

18

The swimmer pushes the water in the backward direction with a certain force

(action) and the water pushes the swimmer in the forward direction with an equal and

opposite force (reaction).

We will not be able to walk if there were no reaction force. In order to walk, we push our foot against the ground. The Earth in turn exerts an

equal and opposite force. This force is inclined to the surface of the Earth. The vertical component of this force balances our weight and the horizontal

component enables us to walk forward.

19