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 = (E)/(T)`

Solving:


`P = (E)/(T)`


`P = (E)/(T) \to T = (E)/(P)`


`T = (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


`(1)/(y) = (60)/(3000)`

Product of extremes equals product of means


`60*y = 1*3000`


`60y = 3000`


`y = (3000)/(60)`


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


I hope this helps! =)

Answer 2

50 minutes

Step-by-step 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