Mechanical Engineering Answers

A refrigerator room has a wall 6m long and 3m high. The wall is built of 120mm thick brick, insulated on the inside with an 80mm layer of cork faced with a thin metal sheet. The coefficient of thermal conductivity of the brick is 1.15W/mK while that of the cork is 0.043W/mK. The exterior brick surface temperature of the wall is 21 degrees Celcius and that of the interior metal faced surface is -4d egrees Celcius throughout. Estimate the heat leakage through the wall in 24 hours and also the temperature of the interface between the cork and brick. 

1. A composite wall is made up of two layers of bricks each 100 mm thick with a 50 mm air space between them. The coefficients of thermal conductivity are
2. Inside brick - 0.6 W/m K
3. Air - 0.025 W/m K
4. Outside brick - 0.8 W/m K
5. The wall is 6.15 m long and 5.5 m high.
6. a. Determine the heat loss per hour through the wall if the inside face temperature is 24^oC and the outside face temperature is 7^oC
7. b. Determine the interface temperatures

3. Find the angle of the largest right circular cone which can be inscribed in a sphere of

radius 9 inches.

4. A statue 10 feet high is standing on a base 13 feet high. If an observer’s eye is 5 feet

above the ground, how far should he stand from the base in order that the angle

between his lines of sight to the top and bottom of the statue is a maximum. (How far

should he stand to get the best view of the statue.

5. A steel girder 27 feet long is to be moved on rollers along a passageway 8 feet in

width and into a corridor at right angles to the passageway. If the horizontal width of

the girder is neglected, how wide must the corridor be in order that the girder can go

around the corner?

At what point on the line y = b does the line segment from (0,0) to ( a,0) subtend the

greatest angle.

n the right triangle ABC, AB = 2, BC = 4 and ED is a line parallel to AB. Find the

angle α = angle BAD which minimizes the distance L, where L = AD + ED

Calculate the maximum value of the e.m.f. generated in a coil which is rotating at 50 rev/s in a uniform magnetic field of 0.8 Wb/m2. The coil is wound on a square former having sides 5 cm in length and is wound with 300 turns

At what stage the sheet metal is called as pattern?

Mention the diagonal angle in scoop making layout?

A single disc clutch with both sides of the disc effective is used to transmit 10 kW power at 900 r.p.m. The axial pressure is limited to 0.085N / m * m ^ 2 If the external diameter of the friction lining is 1.25 times the internal diameter, find the required dimensions of the friction lining and the axial force exerted by the springs. Assume uniform wear conditions. The coefficient of friction may be taken as 0.3.

A 210-ton train has its speed reduced from 40 to 30 miles per hour in 0.50 minute. If the whole of the work done against frictional resistance of the brakes converted into heat, find the heat developed in BTU.