Question

What is the commercial unit of energy. What is the SI unit of Electric energy. A body does 20 joules of work in 5 seconds. What is its power? [5 MARKS]

Answer 1

Definition: 1 Mark
Equation: 1 Mark
Problem: 3 Mark

1. The commercial unit of energy is Kilowatt- hour
2. The SI unit of Electric energy joule.
3. Power is calculated by using the formula:

$Power=\frac{Workdone}{Timetaken}$

Here, Work done = 20 J

And, Time taken = 5 s

So, putting these values in the above formula, we get:

$Power=\frac{20J}{5s}$

$=4J/s$

Thus, Power = 4 W (because 1 J/s = 1 W)

Thus, the power of this body is 4 watts