Solved Example Problems for power

Solved Example Problems for Unit of power

Example 4.18

Calculate the energy consumed in electrical units when a 75 W fan is used for 8 hours daily for one month (30 days).

Solution

Power, P = 75 W

Time of usage, t = 8 hour × 30 days = 240 hours

Electrical energy consumed is the product of power and time of usage.

Electrical energy = power × time of usage = P × t

Solved Example Problems for Relation between power and velocity

Example 4.19

A vehicle of mass 1250 kg is driven with an acceleration 0.2 ms-2 along a straight level road against an external resistive force 500 N.Calculate the power delivered by the vehicle’s engine if the velocity of the vehicle is 30 m s-1 .

Solution

The vehicle’s engine has to do work against resistive force and make vechile to move with an acceleration. Therefore, power delivered by the vehicle engine is