Forces+-+Pt(1)

By : Ming To Wong

Sir Issac Newton (1642 - 1727) was one of the founding fathers of dynamics and with that, he came up with "Newton's Three Laws Of Motion ".

The units of Force are Newtons ( **N** )

An object at rest will stay at rest unless a force acts on it. __**Ex. an apple is on a table, it will stay there until someone pushes it or picks it up , etc.**__
 * Newton's First Law**

Likewise, an object in motion will stay in motion until a force is acted upon __**Ex. a man in space is pushed, that man will be in motion until a meteor hits him or someone else saves him (any external force) etc, etc.**__

A body of mass under a force has an acceleration, the acceleration is proportional to its force and inversely proportional to its mass.
 * Newton's Second Law**
 * __F=M*A__**

When a body exerts a force on a second body, the second body exerts the exact same force but in the opposite direction __**Ex. An apple on a table has a force being exerted by gravity (downwards) ,however the apple is not getting crushed, the table exerts an equal amount of force upwards.**__
 * Newton's Third law**

__**Examples**__

1)What is the force applied to a 10 kg mass which is accelerating at 5 m/s^2?


 * F = M A**
 * F=10 * 5**
 * F=** 50 N

2)What is the mass of a car if 500 N's of force are pushing on it and it accelerates from rest to a velocity of 60 m/s in 3 seconds?


 * F = M A **
 * A = 60 - 0/ 3**
 * A = 20 m/s^2**
 * 500 = M (20)**
 * M = 500 / 20**
 * M =** 25 kg