Question

ESSAY QUESTIONS 8 Define the concepts of energy, work and power and explain how they are related. Provide an example of a conceptual physics problem that might involve all three factors.

Answer 1

In physics, work can be defined as transfer of energy. If one object transfers energy to a second object, then the first object does work on the second object. Unit of work is Joule.

Energy can be defined as the capacity for doing the work. Example of mechanical work is when an object is standing still and we force it to move. The energy of the moving object is called kinetic energy. For an object of mass ‘m’ moving with velocity ‘v’, its energy can be expressed as –

E = (1/2)*m*v^2

Unit of energy is Joule.     

There are two types of energy, first is kinetic energy and the other is potential energy.

Kinetic energy is due to the motion of the object and potential energy is the stored energy.

Power is the work done in a unit of time. In other words, power is a measure of how quickly work can be done. Unit of power is Watt.     

Work, W = F*d

Where F is the force and ‘d’ is the displacement in the direction of the force.

Because energy is the capacity to do work, we measure energy and work in the same units means ‘Joule’.

Power (P) is the rate of energy generation over time.

So, P = E / t

Where E is the energy and ‘t’ is the time.