Atorsion bar is used as a suspension element for a vehicle. the bar has a diameter of 20 mm. it is subjected to a torsional moment of 450 n·m and an axial tensile force of 36.0 kn. draw a stress element on the surface of the bar, and then draw the mohr's circle for the element.

Abrake has a normal braking torque of 2.8 kip in and heat-dissipating cast-iron surfaces whose mass is 40 lbm. suppose a load is brought to rest in 8.0 s from an initial angular speed of 1600 rev/min using the normal braking torque; estimate the temperature rise of the heat dissipating surfaces.

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.