1.
WORK,ENERGY & POWER
SHAHBAZ AHMED
15CH44

2.
Work:
• When a force acts on a body in such a way that body covers some
displacement, it is called work.
• Work(W) is defined as a product of force(F) and displacement(d)
• Work can be defined as transfer of energy.
• Work is scalar quantity.
• InSI unit of work is Joule( J ). J=N×m
• If force makes an angle with the direction of motion, then for finding
work done, that component of force will be taken which acts in the
direction of motion(Fcos ) .W=F cos d
• W=F cos d

3.
Continue…
• (A) When direction of force and displacement is same the work
done is positive
• (B) When direction of force and displacement is opposite the work
done is negative.
• (C) When force and displacement are mutually perpendicular to
each other the work done is zero.

4.
POWER :
• The rate of doing work is known as power.
Power=
𝑤𝑜𝑟𝑘
𝑡𝑖𝑚𝑒
• Power is a scalar quantity.
• Unit of Power is watt or J/s.
• Other common unit is horse power.
• 1hp=746Watt.

5.
Energy:
The ability of doing work is called Energy.
In SI units energy is measured in Joule(J).
Energy is scalar quantity.

6.
ENERGY
Mechanical Non- Mechanical
Kinetic Potential
Linear
Rotational
Gravitational
Elastic
Electric
Magnetic
Light
Sound
Heat

7.
Law of Conservation of energy
• Statement=Energy is neither created nor destroyed, but one form of
energy is converted into an other form of energy, so total energy of
the system remains constant.
• Explanation= In an isolated system from the motion of the
pendulum above law of conservation of energy is proved in
following way.
P.E=100J
K.E= OJ
P.E= O J
K.E = 100 J
A
B