1. FORCES
AN ACTION (PUSH OR PULL) THAT CAN CAUSE CHANGE IN SHAPE, SIZE OR MOTION

2. Types of forces Non contact Contact Nuclear Gravitational Frictional
Tension
Normal
Air resistance
Applied
spring
Non contact
Gravitational
Electrical
Magnetic
Nuclear

3. Mass vs weight
Mass is the quantity of matter (substance) that a body contains. It is a measure of inertia of a body. It is a scalar quantity and has a base unit of kg. It is independent of location
Weight, W is a vector quantity and a derived quantity. Its unit is the Newton (N)…base unit kgm/s2.
- It is the gravitational force of attraction exerted on a body (by the gravitational field of the planet).
- It depends on (i) mass, m of the body and (ii) the gravitational field strength, g (acceleration due to gravity) at the location of the body
- W = mxg …m in kg
A free falling object is an object that is falling under the sole influence of gravity. Any object that is being acted upon only by the force of gravity is said to be in a state of free fall. There are two important motion characteristics that are true of free-falling objects:
Free-falling objects do not encounter air resistance.
All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s2