Mechanical Engineering Answers

An air compressor works with a compression ratio 6:1 . If the incoming air is at a pressure of 1 bar and temperature of 20 degrees °C , calculate the final air pressure if the final temperature is 68 °C . Note : 1bar = 100 * 10 ^ 3 * Pa

A simple hydraulic jack has a pump piston diameter 38.13 mm , and a load piston 190.65 mm . Calculate:

a) the effort force needed to lift a load of 1300 Newton

b) The distance moved by the load if the effort moves a distance 285

A manometer is used to measure the gas pressure supply to a boiler. One side is connected to the supply and the other is open to the atmosphere . The manometer contains water (density 1000 kg/m^ 3 ). Calculate the gauge pressure if the head is 560 mm. How would you find the absolute pressure of the gas supply?

A journal runs in a bearing diameter , 25mm , and length 100 mm at 25 . The clearance gap is 0.8 mm . The lubricant used has a dynamic viscosity of 80 CP . The bearing must carry a side load of 800N . Calculate the values of:

a) the friction force

b) coefficient of friction

Note : 1cP = 1mPa - s

A ball of mass 17.10 kg and diameter 38.13 metre is held fully underwater ( density 1000 kg/m^ 3) Calculate:

a) the upthrust on the ball

b) the density of the ball

c) the percentage of the ball above the surface of the water if it is allowed to float

A storage tank is 4.5 metre wide. It contains a liquid with density 750 kg/m^ 3 to a depth of 7 metre. Calculate the hydrostatic thrust on the side of the tank, and its position from the surface of the liquid.

At a point in an elastic material there are two mutually perpendicular planes, one of which carries a direct tensile stress at 50 N/mm2 and a shear stress of 40 N/mm2, while the other plane is subjected to a direct compressive stress of 35 N/mm2 and a complementary shear stress of 40 N/mm2.

Determine the principal stresses at the point, the position of the planes on which they act and the position of the planes on which there is no normal stress.

Air at a temperature of 100C is compressed at a constant pressure of

1.2MPa from a volume of 2m3 to a volume of 0.4m3. If the initial internal

energy decrease is 4820 KJ, find

a. the work done during the reversible compression

b. the heat transferred

c. the change in enthalpy

shows a 302 stainless steel spring is being applied by a dynamic loading from 150N to

600 N. The spring is peened to induce residual stress on the wire in order to resist fatigue failure. The total number of the coil is shown in Figure Q4 and the spring end is left as squared so that it is able to stand vertically when placed on a flat surface. If the spring index given is 11 and the outer diameter is 66 mm, determine the fatigue factor of safety of this spring. Also, estimate the critical frequency of the spring if the unit weight is given as 76 kN/m².

In Figure below, ω4 = 80 r/min ccw. Determine the number of revolutions per minute of 

link 2 and the velocity of sliding in meters per second at the point of contact. Use a 

velocity scale of 1 mm = 0.0300 m/s.