Tuesday 10 February 2015

FORM 4: 2.10 UNDERSTANDING WORK, ENERGY, POWER AND EFFICIENCY

THE MEANING OF WORK
Work is defined as the product of the applied force and the displacement of an object in the direction of the applied force.
W = F x s
W = work done
F = force
s = displacement in the direction of force
SI unit for work = Joule (J)


WORK FOR OBJECT THAT DOES NOT MOVE IN THE DIRECTION OF THE APPLIED FORCE

W = F s cosθ
No work is done when
1.   a force is applied but no displacement occurs.
2.   an object undergoes a displacement with no applied force acting on it.
3.   the direction of motion is perpendicular to the applied force.


ENERGY
When work is done, energy is transferred from one object to another.
The work done is equal to the amount of energy transferred.
SI unit for energy = Joule (J)

THE MEANING OF KINETIC ENERGY
Kinetic energy is the energy of an object due to its motion.

THE MEANING OF GRAVITATIONAL POTENTIAL ENERGY
Gravitational potential energy is the energy of an object due to its higher position in the gravitational field.

PRINCIPLE OF CONSERVATION OF ENERGY
The principle of conservation of energy states that energy can be transferred from one form to another, but it cannot be created or destroyed.
This means that the total amount of energy always remain the same.

THE MEANING OF POWER
Power is defined as the rate at which work is done.
SI unit of power = Watt (W).

THE MEANING OF EFFICIENCY
Efficiency is defined as the percentage of the energy input that is transformed into useful energy.

No comments:

Post a Comment