Power is defined as the rate of doing work or the rate at which energy is transferred.
Power is the work done per unit time.
Power (P) = Work done (W) / Time (t)
P = W / t
The SI unit of power is watt (W).
One watt is the power when one joule of work is done in one second.
When a force acts on a moving body:
P = F × v
A commonly used larger unit of power is horsepower (hp).
1 hp = 746 W
Q1. Power is defined as: A) Work done B) Energy stored C) Rate of doing work D) Force applied Answer: C Q2. Formula for power is: A) P = F × s B) P = W × t C) P = W / t D) P = m × v Answer: C Q3. SI unit of power is: A) Joule B) Newton C) Watt D) Pascal Answer: C Q4. One watt is equal to: A) 1 J / min B) 1 J / s C) 1 N / m D) 1 N × s Answer: B Q5. Commercial unit of power is: A) Watt B) Joule C) Horsepower D) Newton Answer: C Q6. Relation between power, force and velocity is: A) P = F / v B) P = v / F C) P = F × v D) P = F + v Answer: C Q7. 1 horsepower is equal to: A) 100 W B) 746 W C) 1000 W D) 746 J Answer: B Q8. A machine doing more work in less time has: A) Less power B) More power C) Zero power D) Constant power Answer: B
Power is the rate of doing work.
P = W / t
Watt (W)
P = F × v
Horsepower (hp), 1 hp = 746 W
MCQs and numericals are frequently asked on power formula, unit conversion and relation with force and velocity.
