Question

what is the change in internal energy in a process in which 700j of heat is absorbed and 450j of work done by the system?

Answer 1

$\Delta U=q+w$

Heat absorbed by system, q = 700 J
Work done by the system, w = -450 J (Since work is done by the system negative sign is taken)
$\Delta U$ = 700 + (-450) = 700 - 450 = 250 J
Chnage in internal energy = 250 J