# GCSE Physics

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1. how many kW is 12500 W
12.5 kW
2. how many kW is 7000 W
7 kW
3. how many kW is 500 W
0.5 kW
4. how many kW is 2250 W
2.25 kW
5. how many kW is 15750 W
15.75 kW
6. how many kW is 1500 W
1.5 kW
7. how many kW is 125 W
0.125 kW
8. how many kW is 20 W
0.02 kW
9. how many kW is 35.5 W
0.0355 kW
10. how many hours is 120 minutes
2 hours
11. how many hours is 15 minutes
0.25 hours
12. how many hours is 360 minutes
6 hours
13. how many hours is 75 minutes
0.75 hours
14. how many hours is a week
168 hours
15. how many hours is 30 minutes
0.5 hours
16. a 2000 W electrical fire is used for 10 hours , what is the cost at 8p per kWh
• energy = power * time
• cost = number of kWh * cost per kWh
• 2 kW * 10 = 20 kWh
• 20*8 = 160p
17. if electrical energy costs 9p per unit , calculate the cost of leaving a 3 kW fire switched on for 12 hours
• energy = power * time
• cost = cost per kWh * number of kWh
• 3 * 12 = 36 kWh
• 36 * 9 = 324p
18. if electrical energy costs 9p per unit , calculate the cost of leaving a 120 W T.V. switeched on for 8 hours
• energy = power * time
• cost = cost per kWh * number of kWh
• 0.12 * 8 = 0.96 kWh
• 0.96 * 9 = 8.64p
19. an electric lamp is marked 100 W . find the cost of using it for 6 hours at 8p per unit
• energy = power * time
• cost = number of kWh * cost per kWh
• 0.1*6 = 0.6 kWh
• 0.6 * 8 = 4.8p
20. a 3 kW fire is switched on for 15 minutes . calculate the cost if electrical energy is 9p per unit
• energy = power * time
• cost = number of kWh * cost per kWh
• 3*15/60 = 0.75 kWh
• 0.75 * 9 = 6.75p
21. the diagram below shows an electricity/energy meter
a) how much electricity has been used
b) the electricity costs 9p per unit . whats is the cost of using this quantity of electricity
c) 2047 units are used in the next billing period . What is the new reading on the meter
• cost = number of kWh * price per kWh
• a) 61973-59321= 2652 kWh
• b) 2652 * 9 = 23868p = £238.68
• c) 61973 + 2047 = 64020
22. a 2 kW washing machine for 3 hours if the cost per kWh is 7p
• energy = power * time
• cost = cost per kWh * number of kWh
• 2*3 = 6 kWh
• 6*7 = 42p
23. a 1000 W heater for 2 hours if the cost per kWh is 5p
• energy = power * time
• cost = cost per kWh * number of kWh
• 1*2 = 2 kWh
• 2*5 = 10p
24. a 250 W food mixer for an hour if the cost per kWh is 9p
• energy = power * time
• cost = cost per kWh * number of kWh
• 0.25*1 = 0.25 kWh
• 0.25*9 = 2.25p
25. a 3 kWh tumble drier for 90 minutes if the cost per kWh is 4p
• energy = power * time
• cost = cost per kWh * number of kWh
• 3*90/60 = 4.5 kWh
• 4.5*4 = 18p
26. a 100 W lamp for 30 minutes if the cost per kWh ia 10p
• energy = power * time
• cost = cost per kWh * number of kWh
• 0.1*0.5 = 0.05 kWh
• 0.05 * 10 = 0.5p
27. a 1250 W cooker for 90 minutes if the cost per kWh is 6p
• energy = power * time
• cost = cost per kWh * number of kWh
• 1.25*90/60 = 1.875
• 1.875*6 = 11.25p
 Author: ghoran ID: 147418 Card Set: GCSE Physics Updated: 2012-04-13 12:02:42 Tags: part four Folders: Description: part four Show Answers: