Mechanical Engineering Answers

Unpolarized light falls on two polarizing sheets placed one on top of the other. What must be the angle

between their transmission axis, if intensity of transmitted light by the analyzer is one third of that of

incident light?

A polarizer and analyzer are oriented so that the amount of transmitted light is maximum. Through what

possible angles should either be turned so that the intensity of transmitted light by the analyzer is reduced

to 75% and 25% of the maximum intensity

Two locomotives on opposite banks of river pull a vessel moving parallel to the banks by means of two horizontal ropes. The tension in these ropes are 280 lb force (F1) and 380 lb force (F2), while the angle between them is 70°. Find the resultant pull on the vessel and the angle between each of the ropes (θ1 and θ2) and the sides of the canal

1 kg of air compressed according to the law of PV1.25 = C from 1 bar and 15°C to 17 bar. Calculate the change in entropy. Cp = 1.005 kJ/kg-K and Cv = 0.72 kJ/kg-K.

An inventor claims that his proposed engine has the following specification: Power developed = 50kW; Fuel burnt = 3 kg/hr; Calorific value of the fuel = 75000 kJ/kg; Temperature limits = 27°C and 627°C. Find out whether it is possible or not? 16 K4 CO2

i.In a cyclic process heat transfer are +14.7 kJ, -25.2 kJ,

-3.56kJ and +31.5 kJ. What is the network for the cyclic process?

ii. Apply the steady flow energy equation to a Turbine and deduce an expression for work

A closed system consists of 1 kg of air which is initially at 1.5bar and 67°C. The volume doubles as the system undergoes a process according to the law PV1.2 = C. Find the work done, heat transfer and the change in entropy during this process. For air R= 0.287 kJ/kgK and γ = 1.4

find a homogeneous linear equation with real, constant coefficients that is satisfied by y=6+3xe^x–cos x

Two (2) kg of an ideal gas at 1atm and 300C is placed inside a piston cylinder assembly. Heat was then applied allowing the piston to expand at constant pressure. If the gas has Cp of 1.35kJ/kg-K and Cv of 1.09kJ/kg-K, determine the work done by the gas (kJ) as it is heated to a temperature of 1000C. Determine also the final volume of the gas after expansion (m3).

(a) Derive the formula for elastic potential energy, PEE, in terms of applied force F, stiffness

constant k, and extension ΔL of a wire. State any assumptions made.

(b) Figure 4.6a shows a F versus ΔL graph for a wire of length 2.0 m and diameter 1.2 mm.

(i) Determine the stiffness constant of the wire from the graph.

(ii) Determine the Young’s modulus for the material of the wire.

(iii)What is a practical advantage of knowing the Young’s modulus as compared with the

stiffness constant of the wire?