Useful equations

Efficiency = useful energy output                     Work done = force  x  distance moved
                    total energy input

Power = work done 
              time taken

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1.        Complete the energy transfer diagram opposite

	. heat electricity light potential sound magnetic atomic chemical kinetic		. heat electricity light potential sound magnetic atomic chemical kinetic
			. heat electricity light potential sound magnetic atomic chemical kinetic
			. heat electricity light potential sound magnetic atomic chemical kinetic

3.        A pupil moves a table 2 metres across the floor using a force of 20 newtons. How much work is done?
unit Joules Kilogrammes Newtons Watts

4.       A crane does 4200 joules of work lifting a container a height of 3.5 metres. The weight of the container is                A : 1200 N            B  : 1200 kg         C  : 1200 kJ          D : 14700 N . A B C D

5.        A light bulb is marked 60W, 240V.
a)       What is the power of the bulb?   unit Joules Kilogrammes Newtons Watts

      b)       How many joules of heat and light would be produced each second when the bulb is switched on?

6.        Natalie weighs 550 N. John weighs 600 N. They are both late for the next lesson in an upstairs classroom. There are 10 steps which are each 0.2 metres high. John runs up the steps in 4 seconds.

a)       Calculate the total height that Natalie or John climb. unit Joules Kilogrammes Newtons Watts metres

b)       Calculate the work done by Natalie in climbing the stairs. unit Joules Kilogrammes Newtons Watts metres

c)       How much work is done by John in climbing the stairs?. unit Joules Kilogrammes Newtons Watts metres

d)       How much power does John develop in climbing the stairs?. unit Joules Kilogrammes Newtons Watts metres

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