Q. An inventor claims to have devised a cyclic engine which exchanges heat with reservoirs at 300 K and 540 K, and which can produce 450 J of work per 1000 J of heat extracted from the hot reservoir. Is his claim feasible?
Q. The parallel plates in a capacitor, with a plate area of 9.70 cm2 and an air-filled separation of 2.30 mm, are charged by a 9.10 V battery. They are then disconnected from the battery and pulled apart (without discharge) to a separation of 6.30 mm. Neglecting fringing, find (a) the potential difference (in V) between the plates, (b) the initial stored energy, (c) the final stored energy, and (d) the work required to separate the plates.