Which of the following is an example of a pushing force changing the direction in which an object is moving ?
A. a push from the side on a moving merry-go-round
B. a push from the front on a moving toy car
C. a push from behind on a moving swing
D. all of these

An air standard cycle with variable specific heats is executed in a closed system and is composed of the following four processes. 1-2 isentropic compression 100 kpa and 22°c to 600 kpa 2-3 v=constant heat addition to 1500 k 3-4 isentropic expansion to 100 kpa 4-1 p=constant heat rejection to initial state (a) show the cycle on p-v and t-s s (b) calculate the net work output per unit mass (409 kj/kg) (c) determine the thermal efficiency (47.9%)