## anonymous one year ago 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!!:)

1. Michele_Laino

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

2. anonymous

okay! so 70/1.00*10^3 ?

3. Michele_Laino

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

4. Michele_Laino

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

5. anonymous

ohh oops!! okay so then we get 1428.57 ? so is that choice D?

6. Michele_Laino

yes! that's right!

7. anonymous

yay!! thank you:)

8. Michele_Laino

thanks!! :)