## anonymous one year ago How much work can be extracted from 5.00 × 10^4 J of heat when 2.00 × 10^4 J of heat is exhausted? A. - 7.00 × 10^4 J B. - 3.00 × 10^4 J C. 3.00 × 10^4 J D. 7.00 × 10^4 J ***thank you:)

1. Michele_Laino

I think that we have to apply the first principle of thermodynamics

2. anonymous

ok!

3. Michele_Laino

so, we can write this: $Q = L + \Delta U$

4. Michele_Laino

where Q= 2*10^4 Joules, and \Delat U = 5*10^4 Joules

5. Michele_Laino

oops..\Delta*

6. anonymous

okay!! so we get 70000? so our solution is choice D?

7. Michele_Laino

no,we have: $2 \times {10^4} = L + 5 \times {10^4}$

8. anonymous

ohh oops!! so we get 20000 = L + 50000 L = - 30000 ? so we solution is choice B?

9. Michele_Laino

yes! That's right!

10. anonymous

yay:) thank you!! :)

11. Michele_Laino

thank you!! :D