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Year 9 Examinations - Physics > Work Done > Flashcards

Flashcards in Work Done Deck (11):
1

Work done =
force x distance

Power =
Work done
_____________
Time taken

2

1) calculate the work done lifting a 2N object 1.5m






Work done

Work done = 2 X 1.5 = 3J

3

2) calculate the work done by a cars engine if it provides a force of 2000N and the car travels 1500m




Work done



Work done =
2000 x 1500 = 3,000,000

4

3)calculate the distance a cyclist travels if they exert a force of 500N and uses 15KJ of energy




Work done

Distance =
15KJ = 15,000J

500
_______ = 0.03*m or 3mm
15,000

Distance = 3mm

5

4) calculate the force required by a person who uses 10J of energy to lift an object 50cm




Work done

F = W
____
D

F = 10
_____ = 0.2
50
Force = 0.2

6

1) calculate the power of a light bulb that uses 40J of electricity in 4 seconds





Power

Power = Work done
____________
Time

Power = 40
____ = 10W
4

7

2) calculate the energy used by an aeroplane of power 120 000W in 20 seconds

Energy = power x time


Energy = 120 000 x 20
= 2 400 000

8

3) calculate the power of a kettle that uses 200J of energy in half a minute

Power = 200
_____
30
= 6.6W

9

4) Calculate the work done by a bulldozer of power 5000W in 15 seconds

Work done = 5000 x 15

= 75 000J

10

5) calculate the energy used by a heater of power 1.2KW in 1 hour.

1.2KW = 12 000W
1 hour = 60 minutes

Energy = power x time

Energy = 12 000 x 60
= 720 000

11

6) how long does it take a microwave of power 0.2KW to use 10 000J of energy?

Time = power
________
Energy

Time = 12 000
________ = 2000W
6