o level physcis notes

Force is that which changds a bodys state of rest or of uniform motion in a straight
line.
Weight
The weight of a body with respect to the earth is that force which the body exerts on
anything which freely supports it.
Action and reaction are equal and opposite.

Hookes law
When a spring is fixed at one end and a force is applied at the other, the extension
of the spring is proportional to the force applied provided the force is not large
enoggh to stetch the spring permanently.
Scalar quantity and Vector quantity.
A scalar quantity is one which has onl y maggitude or size. A vector quantity has both
magnitude and direction.
The parallelogram of forces
If two forces acting at s point are represented bboth in magnitude and direction
by the adjacent side of a parallelogram, their resultant will be represented both in
magnitude and direction by the diagonal of the parallelogram drawn from the point.
Triangle of forces
If three forces acting at a point are in equilibrium, they can be represented in
magihitude and direction by the three sides of a triangle taken oin order.
Pr&nciple of moments
When a body is in equilibrium: the sum of the anticlockWise moments about any point
is equal to the sum of the clockwise moments.
Equal and opposite forces form what is called a couple.
Centre of gravity
The centre if gravity of a body is defined as the point of application of the resultant
force due to the earts attraction on it.
Speed
Speed is defined as the rate of change of distance moved with time.
Velocity
Velocity is defined as the rate of change of distance moved with time in a specified
direction
Acceleration
Acceleration is defined as the rate of change of velocity moved with time.
Pendulum
A simple pendulum is defined as a small heavy body suspended by a light inextensible
string.
Parallelogram of velocities
If a body has two component velocities which are represented by two adjacent sides of
a parallelogram then the resultant velocity is represented by the diagonal of the
parallelogram drawn from the inersection of the two sides.