Work, Energy and Power

Question 1

Define work done

Answer 1

Work done by a force on a body is the product of the force and the displacement in the direction of the force.

Question 2

Principle of Conservation of Energy

Answer 2

Energy can neither be created nor destroyed, but it can be transformed from one form to another.

Question 2

Define power

Answer 2

Power is the rate at which work is done. (P=E/t)
Power is the product of force and velocity in the direction of the force. (P=fv)

Question 2

Define efficiency

Answer 2

Efficiency is the ratio of useful energy output to the energy input, expressed as a percentage.

Question 3

Derive KE equation from work done equation

Answer 3

Wd = Fs
Since F = ma
Wd = mas – eqn 1

v² = u² + 2as
as = 0.5(v² - u² ) –eqn 2

sub tgt:
Wd = 0.5m(v² - u²)
Wd = △KE
Simplify: W = (1/2)mv².

Question 3

work-energy theorem

Answer 3

Net work done on a body is equal to the change in kinetic energy of the body.