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## Homework Statement

The power supplied by a certain battery is a constant 6 W over the first 5 min, zero for the following 2 min, a value increases linearly from zero to 10 W during the next 10 min, and a power that decreases linearly from 10 W to zero in the following 7 min. (a) What is the total energy in joules expended during this 24 min interval? (b) What is the average power in Btu/h during this time?

## Homework Equations

[tex]P_{T} = P_{1} + P_{2} + P_{3} + P_{4}[/tex]

## The Attempt at a Solution

I think I just find the power for the various times and add them up.

What I am confused with is when it says 6 W constant over 5 min does it mean:

[tex]P_{1} = (6 W)(5 min) = 30 W/min[/tex]

or does it mean:

[tex]P_{1} = 6 W[/tex]

then [tex]P_{2} = 0[/tex]

and I am lost on what to do about [tex]P_{3}[/tex] and [tex]P_{4}[/tex]