Basic Definitions in Physics
Below are some basic definitions in physics
that you are likely to need or come across when studying
physics at school.
Speed
Speed is the rate of change of distance.
Velocity
The velocity is the rate of change of
displacement.
Acceleration
The acceleration is the rate of change of
the velocity.
Newton's Laws
1st: Newton's First law
states that every body continues in its state of rest or of
uniform motion in a straight line unless acted on by some
external force.
2nd: Newton's Second
Law states that the rate of change of momentum of a body is
directly proportional to external force acting on the body
and takes place in the direction of the force.
3rd: If a body A exerts
a force on a body B, then B exerts an equal and opposite
directed force on A.
Linear Momentum
The linear momentum is the product of mass
and velocity.
Force
The force is the rate of change of
momentum.
Conservation of Momentum
The conservation of Momentum states that the
total (linear) momentum of a system of interacting bodies, on
which no external forces are acting, remains constant.
Moment of a force
The moment of a force = force x
perpendicular distance from the pivot to the line of action of
the force.
Torque of a couple
The torque of a couple or pair of equal and
opposite parallel forces lines of action do not coincide is the
product of one or the forces and perpendicular distance between
the lines of action.
Potential at a point
The potential at a point is the workdone in
bringing unit mass from infinity to the point.
