Question

a system is given 400 calories of heat and 1000 joule of work is done by the system, then the change in internal energy of the system will be

Answer 1

4oo calories =1673.6 Joule

∆Q = ∆U(total internal energy) +Work done (W)
1673.6 = ∆u + 1000

∆U = 673.6

Answer 2

Answer:

The change in the internal energy of the system will be 680 Joule.

Explanation:

From the first equation of thermodynamics we have,

$\Delta U=Q-W$       (1)

Where,

ΔU=change internal energy

Q=heat supplied to a system

W=work done by the system

From the question we have,

The heat given to a system (Q)=400 calories=1680 Joule        (1calorie=4.2Joule)

Work done by the system (W)=1000 Joule

By placing the value of Q and W in equation (1) we get;

$\Delta U=1680-1000$

$\Delta U=680\ Joule$

Hence, the change in the internal energy of the system will be 680 Joule.

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