Extra Sheet: Power (Grade 8)

Rule: Power is the rate at which work is done or energy is transferred. It is calculated by dividing the work done or energy transferred by the time taken.

Formula: Power (P) = Work done (W) / Time taken (t)

Example 1: A machine does 500 Joules of work in 10 seconds. Calculate the power of the machine.

Solution: Power (P) = Work done (W) / Time taken (t) P = 500 J / 10 s P = 50 Watts

Example 2: A motor transfers 1000 Joules of energy in 5 seconds. Find the power of the motor.

Solution: Power (P) = Energy transferred (W) / Time taken (t) P = 1000 J / 5 s P = 200 Watts

Extra Exercise: 1. A person lifts a box weighing 200 N to a height of 2 meters in 5 seconds. Calculate the power exerted by the person. 2. A car engine does 5000 Joules of work in 10 seconds. Find the power of the car engine. 3. A light bulb transfers 1000 Joules of energy in 2 seconds. Calculate the power of the light bulb. 4. A wind turbine generates 5000 Watts of power in 1 hour. Find the energy generated by the wind turbine. 5. A machine transfers 8000 Joules of energy in 4 seconds. Calculate the power of the machine.

Note: Remember to use the appropriate units (Joules, Watts, Newtons, meters, seconds, etc.) in your calculations.