Question

Suppose a woman does 500 J of work and 9500 J of heat transfer occurs into the environment in the process. (a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer.) (b) What is her efficiency?

Answer 1

Answer:

The change in internal energy and efficiency are 10000 J and 5.26%.

Explanation:

Given that,

Work = 500 J

Heat transfer = 9500 J

(a). We need to calculate the decrease in her internal energy

Using equation of internal energy of a system

$\Delta U=Q-W$

Q = heat

W = work done

Put the value into the formula

She looses her heat -9500 J

$\Delta U=-9500-500$

$\Delta U=-10000\ J$

(b). We need to calculate the efficiency

Using formula of efficiency

$e=\dfrac{W}{Q}$

$e=\dfrac{500}{9500}$

$e=0.0526\times100$

$e=5.26\%$

Hence, The change in internal energy and efficiency are 10000 J and 5.26%.