An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joules per second. At what rate is the internal energy increasing?

The side of a square increases at therate of 1 cm per second. The rate at which perimeter increases is

Heat given to a system is 35 joules and work done by the system is 15 joules. The change in the internal energy of the system will be

Heat of 30 kcal is supplied to a system and 4200 J of external work is done on the system so that its volume decreases at constant pressure. What is the change in its internal energy. (J=4200 J/kcal)