Question

If the efficiency of a heat engine that does 1.00 × 10^3 J of work is 70 percent, then what is the heat input?

A. 1.43 × 10 J

B. -7.00 × 10^2 J

C. 9.30 × 10^2 J

D. 1.43 × 10^3 J

**Not sure! thanks!!:)

Answer 1

by definition, the efficiency is given by the subsequent formula:
\[\eta = \frac{L}{Q}\]

Answer 2

okay! so 70/1.00*10^3 ?

Answer 3

no, it is:
\[Q = \frac{L}{\eta } = \frac{{{{10}^3}}}{{0.7}}\]

Answer 4

\[\Large Q = \frac{L}{\eta } = \frac{{{{10}^3}}}{{0.7}}\]

Answer 5

ohh oops!!

okay so then we get 1428.57 ? so is that choice D?

Answer 6

yes! that's right!

Answer 7

yay!! thank you:)

Answer 8

thanks!! :)