1. Chapter 12.2

2. Aristotle Ancient Greek Scientist
Observations and logical reasoning provided scientific discoveries.
Incorrectly proposed that force is required to keep an object moving at constant speed
Held back the study of motion for thousand years

3. Galileo Italian scientist Experimented to find out about the world
Studied how gravity produces constant acceleration
Concluded that moving objects were not subjected to friction or any other force.

4. Newton Newton studied at Trinity college but were forced to leave.
He built his ideas based on Galileo.
He defined mass and force
Introduced his laws of motion

5. Newton's First Law .
Newton´s first law is often called the law of inertia
Newton´s First Law of Motion states – An object at rest will remain at rest, or an object in motion will remain in motion in a straight line at constant speed, unless an external force is applied to it and changes its state motion

6. Newton's Second Law .
The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass
F=ma
Force = mass x acceleration
Units
Force = Newtons or Kg m/s^2
Mass = kilograms
Acceleration = m/s/s or m/s^2

7. Newton's Third Law .

8. Problem
If an astronaut has a mass of 112 kilograms, what is his weight on Earth where the acceleration due to gravity is 9.8 m/s^2 ?
Weight = Mass x Acceleration due to gravity
= 112kg x 9.8 m/s^2
= 1100 kg*m/s^2 = 1100 N

9. Thanks!