If the amount of heat given to a system is 35 J and the amount of work done on the system is 15 J, then the change in internal energy of the system is

If the amount of heat given to a system is 35 J and the amount of work

1.	If the amount of heat given to a system is 35 J and the amount of work done on the system is 15 J, then the change in internal energy of the system is
Answer» `-50 J` 20J `-20 J` 50 J Solution :According to first law of THERMODYNAMICS `DELTA Q = Delta U + Delta W` or `Delta U = Delta Q - Delta W` here , `Delta Q = 35 J, Delta W = -15 J :. Delta U = 35 J - (-15 J) = 50 J` NOTE :`Delta W` is negative because work done on the SYSTEM.