The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is

Question

The internal energy change in a system that has absorbed 2 kcal of heat and done 500 J of work is (A) 6400J (B) 5400J (C) 7900J (D) 8900J

Tardigrade Admin · Accepted Answer

Heat energy given d Q=d U+d W where d U is the change in internal energy and d W is the work done. Given d Q=2 kcal =2000 × 4.2 J and d W=500 J ∴ d Q=2000 × 4.2=d U+500 ⇒ d U=7900 J

Q. The internal energy change in a system that has absorbed $2 k c a l$ of heat and done $500 J$ of work is

6400J

5400J

7900J

8900J

Heat energy given $d Q = d U + d W$
where $d U$ is the change in internal energy and $d W$ is the work done.
Given $d Q = 2 k c a l = 2000 \times 4.2 J$ and $d W = 500 J$
$∴ d Q = 2000 \times 4.2 = d U + 500$
$\Rightarrow d U = 7900 J$

Q. The internal energy change in a system that has absorbed 2kcal of heat and done 500J of work is