48.two 5-cm-diameter, 15-cm-long aluminum bars (k=176w/m°c) with ground surfaces are pressed against each other with a pressure of 20 atm. the bars are enclosed in an insulation sleeve and, thus, heat transfer from the lateral surfaces is negligible. if the top and bottom surfaces of the two-bar system are maintained at temperatures of 150°c and 20°c, respectively. determine: a) the rate of heat transfer along the cylinders under steady conditions; b) the temperature drop at the interface

Amass of 1.5 kg of air at 120 kpa and 24°c is contained in a gas-tight, frictionless piston-cylinder device. the air is now compressed to a final pressure of 720 kpa. during the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. calculate the boundary work input during this process.

What difference(s) did you notice using a pneumatic circuit over hydraulic circuit.explain why the pneumatic piston stumbles when it hits an obstacle.

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.