Question

A system release 100kj of heat with 95kj of work done is on the system calculate the change in internal energy​

Answer 1

Given:

A system release 100kj of heat with 95kj of work done is on the system.

To find:

Change in internal energy.

Calculation:

According to Thermodynamics , when heat is released from a system ∆Q will be denoted by negative sign. When work is done on system , work will be negative.

Applying 1st Law of thermodynamics:

$\therefore \: \sf{\Delta Q = \Delta \: U + W}$

$= > \: \sf{ - 100 = \Delta \: U + ( - 95)}$

$= > \: \sf{ - 100 = \Delta \: U - 95}$

$= > \: \sf{ \Delta \: U = - 100 + 95}$

$= > \: \sf{ \Delta \: U = -5 \: kJ }$

So, the final answer is:

$\boxed{ \red{ \bold{ change \: in \: internal \: energy = \Delta \: U = -5 \: kJ }}}$

• Always remember that in physics, the work done is positive when the work is done by system and the formula to be applied is ∆Q = ∆U +W.