Select the best answer for the question.
13. in a normally operating engine, intake and exhaust valves are opened by a cam and closed
o a. rocker arms or cam follower.
o b. lifters/tappets.
c. valve springs.
od. valve guides and/or pushrods.

For each of the following process: a) sketch the p-v diagram, b)sketch t-s diagram, c) sketch t-v diagram, d) sketch the boundary work on one of the diagrams (a, b or c) and e) sketch the reversible heat transfer on one of the diagrams (a, b or c): 1- isobaric process from compressed liquid to superheated vapor 2- isothermal process from compressed liquid to superheated vapor 3- isentropic process from compressed liquid to superheated vapor