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# Solved Example Problems for power

Physics : Work, Energy and Power : 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

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11th Physics : UNIT 4 : Work, Energy and Power : Solved Example Problems for power |