Question

A 3kW oven supplied with 9mJ of energy.How many minutes can it run for?

Answer 1

Hello!
 
We have the following data:

Time (T) = ? (in minutes)
Power (P) = 3 kW → 3000 W
Energy (E) = 9 MJ → 9000000 J or (W/s)

Formula of the consumption of electric energy:

$P = \frac{E}{T}$

Solving:

$P = \frac{E}{T}$

$P = \frac{E}{T} \to T = \frac{E}{P}$

$T = \frac{9000\diagup\!\!\!\!0\diagup\!\!\!\!0\diagup\!\!\!\!0\:\diagup\!\!\!\!W/s}{3\diagup\!\!\!\!0\diagup\!\!\!\!0\diagup\!\!\!\!0\:\diagup\!\!\!\!W}$

$\boxed{T = 3000\:seconds}$

How many minutes can it run for? (Let's convert in minutes)

1 minute --------- 60 seconds
y minute --------- 3000 seconds

$\frac{1}{y} = \frac{60}{3000}$

Product of extremes equals product of means

$60*y = 1*3000$

$60y = 3000$

$y = \frac{3000}{60}$

$\boxed{\boxed{y = 50\:minutes}}\end{array}}\qquad\quad\checkmark$


I hope this helps! =)

Answer 2

Answer:

50 minutes

Explanation:

Power, P = 3 kW = 3000 W

Energy, E = 9 MJ = 9 x 10^6 J

Let the time be t.

Power = Energy / time

Time, t = E / P = 9 x 10^6 / 3000 = 3000 sec

t = 50 minutes