For the cases below, a closed system undergoes a process in which work is done on the system and the heat transfer Q occurs only at a location on the boundary where the temperature is Tb. For each case, determine whether the entropy change of the system is positive, negative, zero, or indeterminat. a. internally reversible process, Q > 0.b. internally reversible process, Q = 0.c. internally reversible process, Q < 0.d. internal irreversibilities present, Q > 0.e. internal irreversibilities present, Q = 0.f. internal irreversibilities present, Q < 0.

An electrical motor raises a 50kg load at a construct velencity .calculate the power of the motor, if it takes 40sec to raise the load through a height of 24m(take g =9.8n/g)

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length