Question

Calculate the work don in j by the following [a] a 10kw heater running for 15 minutes [b] two 100 w light bulbs on for 24 hours

Answer 1

Answer:

A ) 2.5 kWh

B ) 4.8 kWh

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Answer 2

Answer:a) 9000000j

Explanation: since , 1W=1j/sec

And ,1Kw= 1000j/sec

So,10Kw=(10×1000)j/sec= 10000joulesj/sec.

Energy required by heater in 1sec is equal to 10000 j.

Heater runs for 15 minute

So, work =energy =10000j/sec×(15×60)= 9000000 joules.

Similary, second one .

Work done by bulb per second is 100j. Therefore, work done by bulb for 24 hours = 100j/sec×(24×60×60)sec=864000j.