A yo-yo [see Fig (a)] is constructed from two identical uniform disks of radii R and mass M They are held together by a massless cylindrical spindle [hub of smaller radius Ro. The yo-yo is wound with very thin, massless string. 0- The yo-yo is released from rest and falls/unwinds for a distance of h
(a) What is angular acceleration during the descent?
(b) What is the tension on the string during the descent?
(c) How long does it take to descend to the distance h?

An ideal otto cycle has a compression ratio of 8. at the beginning of the compression process, air is at 95 kpa and 27°c, and 750 kj/kg of heat is transferred to air during the constant-volume heat-addition process. assuming constant specific heats at room temperature, determine (a) the pressure and temperature at the end of the heat-addition process, (b) the net work output, (c) the thermal efficiency, and (d) the mean effective pressure for the cycle. (4390 kpa, 1730 k; 423 kj/kg; 56.4%; 534 kpa)