# Mechanical Engineering

## One side of a 2-m-high and 3-m-wide vertical plate at 80°C is to be cooled by attaching aluminum fins (k= 237 W/m-K)

Question: One side of a 2-m-high and 3-m-wide vertical plate at 80°C is to be cooled by attaching aluminum fins (k= 237 W/m-K) of a rectangular profile in an environment at 35°C. The fins are 2 cm long, 0.3 cm thick, and 0.4 cm apart. The heat transfer coefficient between the fins and the surrounding …

## Calculate the moment created by the forces shown in the accompanying figure about point O.

Question: Calculate the moment created by the forces shown in the accompanying figure about point O. Answer:

## The following data were collected from a 0.4-in.-diameter test specimen of polyvinyl chloride (l0 = 2.0 in.):

Question: The following data were collected from a 0.4-in.-diameter test specimen of polyvinyl chloride (l0 = 2.0 in.): Load (lb) Δl (in.) 0 0.00000 300 0.00746 600 0.01496 900 0.02374 1200 0.032 1500 0.046 1660 0.070 (maximum load) 1600 0.094 1420 0.12 (fracture) After fracture, the total length was 2.09 in. and the diameter was 0.393 in. …

## A pair of helical gears is to be designed to transmit 5.0 hp while the pinion rotates at 1200 rpm

Question: A pair of helical gears is to be designed to transmit 5.0 hp while the pinion rotates at 1200 rpm. The gear drives a reciprocating compressor and must rotate between 385 and 390 rpm. Answer:

## Because of relief of residual stresses during curing

Question: Because of relief of residual stresses during curing, long unsupported overhangs in parts made by stereolithography tend to curl. Suggest methods of controlling or eliminating this problem. Answer: Problem regarding curls are minimized by ceilings or gussets used to hold the material and minimize curl during curing. This can also be minimized in design …