Work, Power, Efficiency

Question 1

Meaning of ‘work’

Answer 1

Work done is the energy used doing a job

Question 2

Equation and units for work

Answer 2

W=FxS
Work is in J
S (displacement) is in m
Force is in N

(Or equation might be shown as W=Fxd
Distance rather than displacement)

Question 3

Meaning of efficiency and give the equation

Answer 3

Percentage of energy supplied that is used usefully

Efficiency=useful energy/total energy supplied

Question 4

Meaning of power and give the equation

Answer 4

Power is the rate of energy transfer

P= E/T
Power is in watts
Energy is in J
Time is in s