A watt is often described as a joule transferred per second.

PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy

Problem

A watt is often described as a joule transferred per second. (i) State clearly what is meant by the statement 1 W=1 J s−11\,\text{W}=1\,\text{J s}^{-1}. Give a short verbal explanation. (ii) Show numerically that 1 kW=6×104 J min−11\,\text{kW}=6\times10^{4}\,\text{J min}^{-1}. Write every conversion step. (iii) A microwave oven carries the rating "800 W". Explain, with calculation, how much energy in joules it transfers in 30 s30\,\text{s}. Also state in words what this value signifies for the user.

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