Engineering Answers

Say that you buy a house for $250,000 (for simplicity let's assume you pay 100% cash). Six years later, you decide to sell the house maybe your family is growing and you need to move into a larger place. You are able to sell the house for $335,000, after deducting any realtor's fees and taxes. Find simple rate of return on the purchase and sale of the house.

Brigham Tea, Inc., is a processor of low acid tea. The company is contemplating purchasing equipment for an additional processing line. The additional processing line would increase revenues by $90,000 per year. Incremental cash operating expense would be $40,000 per year. The equipment would cost $180,000 and have a nine-year life. No salvage value is projected.

Twelve people are given two identical speakers. which they are asked to listen to for differences, if any. Suppose that these people answer simply by guessing. Find the probability that three people claim to have heard a difference between the two speakers.

An employee is selected from a staff of 10 to supervise a certain project by selecting a tag at random from a box containing 10 tags numbered from 1 to 10. (a) Find the formula for the probability distributions of X representing the number on the tag that is drawn. (b) What is the probability that the number drawn is less than 4? (c) Find the mean and variance of the random variable X.

A 300mm square column is reinforced with 3Φ16 bars at each of the two critical faces. If C25 concrete and steel with fyk=300MPa is used, compute the ultimate axial compressive force the section can safely resist.

A tank of volume 0.00354 m³ contains 0.00292 kg of saturated water vapour at 0.143 MPa. A line is attached to the tank in which water vapour flows at 0.7 MPa and 200 °C. Steam from this line enters the tank until the pressure in the tank is 0.7 MPa.

                             i)     Why can this process be analysed as uniform flow?

[2 marks]

ii) State THREE assumptions, other than uniform flow, that must be made when analysing this process.

[3 marks]

ii)              Use the mass balance to write an expression for the final mass of steam, m₂, in the tank.

[2 marks]

iii)            Write an expression for the energy balance for the system based on the assumptions made in part (ii) and calculate the mass of steam that enters the tank. The properties of steam under these conditions are:

h_in = 2845.3 kJkg^-1 u₁ = 2517.6 kJkg^-1 and u₂ = 2749.9 kJkg^-

1

[5 marks] v) Predict and explain what would happen to the temperature of the steam in the tank during this process.

[3 marks] 

Drive pulley A with a diameter of 200 mm , drives pulley B with a diameter of 800 mm by means of a belt drive. IF pulley B is uniformly accelerated from 69 r/min to 240 r/min calculate

(a) The angular acceleration of each pulley

(b) The linear acceleration of the belt if slip is ignored

(C) The initial velocity of pulley A in r/min and the final velocity of pulley A in rad/s.

17. The moisture removed from a material is 200 lb/hr and change of humidity ratio in dryer is 0.015. Determine the fan capacity if specific volume of air entering is 38 ft3/lb. Please the answer with solution.

16. Find the dew point temperature of air whose humidity ratio is 0.0150 kg water/kg dry air. Please the answer with slution.

14. A cooling tower cools water from 39oC to 24oC at the rate of 25 kg/s. Air enters the tower at 18oC at the rate of 35 kg/s. Find the temperature of air leaving the tower. Please explain the answer with solution.