Question

what is the change in internal energy for a system that does 70 j of work as it absorbs 45 J of heat​

Answer 1

$\Large{\underline{\underline{\bf{Solution:}}}}$

According to law of thermodynamics,

$\Large{\implies{\boxed{\boxed{\sf{dU = dQ - dW}}}}}$

Where,

• dU = Change in internal energy

• dQ = Heat energy absorbed by the system

• dW = Work done by the system

Now, A.T.Q

dQ = + 70 J

dW = - 45 J (As the work done is on the surroundings we get a negative sign)

On substituting the values

dU = 70 - (- 45)

dU = 70 + 45 = 115

Therefore the change in internal energy is 115 J