MD 3 - Looks Fam Problems Flashcards
Pressurized water at 1.37 Mpa is stored in a
steel cylindrical tank 1.4 meters in diameter.
If the allowable tangential stress is 8.5 Mpa,
find the required wall thickness of the tank.
a)123.6 mm
b)130.5 mm
c)112.9 mm
d)135.1 mm
123.6 mm
A mechanical press is used to punch 6 holes per holes
is 25 mm diameter and the plates has an ultimate
strength in shear of 420 Mpa. The normal operating
speed 200 rpm. And it slows down to 180 rpm during
the process of punching. The flywheel has a mean
diameter of one meter and the rim width is 3 time
sthe thickness. Assume that the hub and arm account
for 5% of the rim weight concentrated at the mean
diameter and the density of cast iron is 7200 kg per
cubic meter. Find the power in kW required to drive the press.
a) 1.310 kW
b) 5.57 kW
c) 8.92 kW
d) 9.03 kW
1.310 kW
Find the weight of the flywheel needed by a machine to punch 20.5 mm holes in 15.87 mm thick steel plate. The machine is to make 30 strokes per minute and a hole be punched every stroke, the hole is to be formed during 30 degrees rotation of the puncher crankshaft. A gear train with a ratio of 12 to 1 is to correct the flywheel shaft to the crankshaft. Let mean diameter of a flywheel rim to the 91.44 cm. the minimum flywheel speed is to be 90% of the maximum and assume mechanical efficiency of the machine to be 80% Assume an ultimate stress of 49000 psi.
a) 68 kg
b) 97 kg
c) 90 kg
d) 92 kg
97 kg
It is found that the shearing machine requires 205joules of energy to shear a specific gauge of sheet metal. The mean diameter of the flywheel is to be76.2 cm. the normal operating speed is 200rpm and slow down to 180 rpm during shearing process. The rim width is 30.48 cm and the weight of cast iron is7,196.6 kg/m^3, find the thickness of the rim, assuming that the hub and arm account for 10% of the rim weight concentrated on the mean diameter.
a) 0.583 cm
b) 0.587 cm
c) 0.672 cm
d) 0.480 cm
0.587 cm
A tubular shaft, having an inner diameter of30 mm and an outer diameter of 42 mm, is to be used to transmit 90 kW of power, determine the frequency of rotation of the shaft so that the shear stress cannot exceed 50 Mpa.
a) 26.6 Hz
b) 20.6 Hz
c) 97.5 Hz
d) 66.5 Hz
26.6 Hz
