Question

System with internal energy E1 absorbs 200 calorie of heat and work done on it is 1 calorie.the final internal energy is equal to ?

Answer 1

The final internal energy is equal to (E1 + 199) cal

Solution :

We know that the change in internal energy will be equal to the heat absorbed minus the work done because the heat absorbed is utilised in increasing the internal energy and work done.

Hence,

ΔU = Q - W

where,

ΔU = change in internal energy

Q = heat absorbed = 200 cal

W = work done = 1 cal

Hence

ΔU = 200 - 1 = 199 cal

We know that,

Final internal energy = Initial internal energy + ΔU

= E1 + 199 cal

Hence the final internal energy is equal to (E1 + 199) cal