The sum of two expressions
1 answer:
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Answer:
1. 600 watts
2. 35640 J
3. 55%
4. 20 J
5. The cost of running the fire is 8p.
Step-by-step explanation:
1. Energy = 36 000 J , t = 1 minute = 60 seconds
Power =
=
= 600 watts
2. Power =
⇒ work done = Power × time
= 99 × 360
= 35640 J
3. Efficiency = (Output / Input) × 100
= × 100
= 55%
4. Work done = Force × distance
= 5 × 4
= 20 J
5. Given that 1 KWh cost 2p, Power = 4 KW and time = 4 hours.
Power =
Energy = Power × time
= 4 × 4
= 16 KWh
The cost of running the fire =
= 8p