Engineering Answers

A compound cylinder is formed by shrinking a tube of 200mm outside and 150mm inside diameter on to one of 150mm outside and 100mm inside diameter. Owing to shrinkage the radial stress at the common surface is 20 MN/m². If this cylinder is now subjected to an internal pressure of 100 MN/m², what is the magnitude and position of the maximum hoop stress?

5.) A worker borrowed money on April 20, 1995 and promised to pay 18,000 on march 4, 1996 with 16% interest. Determine the money he has borrowed using exact interest.

8.) P 8500 is borrowed for 70 days at 18% per annum. How much will be due at the end of 70 days? Use exact simple interest.

7.) A certain amount of money triples after 9 years. determine its effective interest.

By what percentage would the rate of absorption be increased or decreased by increasing the total pressure from 100 to 200 KN/m2 in the following cases:

a. The absorption of ammonia from a mixture of ammonia and air containing 10% of ammonia by volume, using pure water as solvent. Assume that all the resistance to mass transfer lies within the gas phase.

b. The same conditions as (a) but the absorbing solution exerts a partial vapour pressure of ammonia of 5 KN/m2. The diffusivity can be assumed to be inversely proportional to the absolute pressure.

By what percentage would the rate of absorption be increased or decreased by increasing the total pressure from 100 to 200 KN/m2 in the following cases: a. The absorption of ammonia from a mixture of ammonia and air containing 10% of ammonia by volume, using pure water as solvent. Assume that all the resistance to mass transfer lies within the gas phase. b. The same conditions as (a) but the absorbing solution exerts a partial vapour pressure of ammonia of 5 KN/m2. The diffusivity can be assumed to be inversely proportional to the absolute pressure.

an oxygen cylinder of volume 2.3 cubic foot has a pressure of 2200 psi gauge and is 21 degrees Celsius. Determine the mass of oxygen in the cylinder

A reheat cycle with two stages of reheating is executed, with steam expanding initially from 90 bar and 530 deg. C. The two reheater pressures are 10 bar and 0.6 bar, and the steam leaves each reheater at 480 deg. C. Condensation occurs at 0.03 bar. For an ideal cycle, find:

a. Q_a and e

b. For the engine, ignore the pressure drop through the reheaters, let the engine operate through the same states, and compute W and e.

c. What is the steam flow rate for an engine output of 20,000 kW?

A 50m tape of standard length has a weight of 0.05 kg/m, with a cross sectional area of 0.04 sq.cm. It has a modulus of elasticity of 2.10 x 106 kg/cm2 . The tape is of standard length under a pull of 5.5 kg when supported throughout its length and temperature of 20°C. This tape was used to measure a distance between A and B and was recorded to be 458.65 meters long. At the time of measurement, the pull applied was 8kg with the tape supported only at its end points and the temperature observed was 18°C. Assuming coefficient of linear expansion of the tape is 0.0000116/°C.

(a) Compute the correction due to the applied pull of 8 kg.

(b) Compute the correction due to weight of tape. 

(c) Compute the true length of the measured line AB due to the combined effects of tension, sag and temperature. 

A bronze tube, 60mm external diameter and 50mm bore, fits closely inside a steel tube of external diameter 100mm. When the assembly was at a uniform temperature of 15°C the bronze tube is a sliding fit inside the steel tube, that is the two tubes are free from stresses. The assembly is now heated to a uniform temperature of 115°C.

(a) Calculate the radial pressure induced between the mating surfaces and the thermal circumferential stresses, in magnitude and nature, induced at the inside and outside surfaces of each tube.

(b) Sketch the radial and circumferential stress distribution across the combined wall thickness of the assembly when the temperature is 115°C and insert the numerical values. [ E for steel = 200 GN/m² E for Bronze = 100 GN/m², poisson's ratio for steel = 0.3 poisson's for Bronze = 0.33, coefficient of linear expansion for steel = 12×10-⁶/°C and coefficient of linear expansion for Bronze = 19×10-⁶/°C]