15: 1-work And Energy : Cbse-ix-science

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Qstn #3
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Ans : P = W/t = 1000J/10s = 100 W

Qstn #4
Define average power.
Ans : An agent may not be able to perform same amount of work in a given period of time always. In other words, power of that agent may vary with time. Hence we can take average power in such situations. Average power is defined as average amount of work done by a body per unit time (i.e. total energy consumed divided by total time).