Work: if a body
gets displaced when a force acts on it, work is said to be done. Work is
measured by the product of force and displacement of the body along the
direction of force.
If a body gets
displaced by S when a force F acts on it, then the work W = F S cosθ
Where θ = angle between force and displacement
If both force and displacement are in the same direction,
then W= FS
Work is a scalar quantity and its SI unit is joule.
Energy: Capacity
of doing work by a body is called its energy.
Energy is a scalar quantity and its SI unit is joule.
Energy developed n a body due to work done on it is called
mechanical energy. Machanical energy is of two types:
(i)
Potential
Energy (ii) Kinetic Energy
Potential Energy:
The capacity of doing work developed in a body due to its position or
configuration is called its potential energy.
Example: (i)
energy of stretched or compressed spring (ii) energy of water collected at
height (iii) energy of spring in a watch.
PE of a body in the gravitational field of earth is mgh.
Where m= mass, g= acceleration due to gravity, h= height of the body from surface of
the body.
Kinetic Energy:
Energy possess by a body due to its motion is called kinetic Energy of the
Body.
If a body of mass m
is moving with speed v, then kinetic
energy of the body is ½ mv²
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