Mechanical Engineering Answers

The electric current i flowing in a device varies with time t. The equation linking the two variables is as follows.
i=2sin(5t)
The area under the graph represents the charge q that has passed over any given time interval.
Calculate the area and hence the charge by integrating the equation between t=t1 and t=t2
t1=0.4
t2=0.5

A block of material 150mm x 50mm x 75mm has a shear modulus of 50 Gpa. Determine the shear stress and the shear strain induced by the 2kN shearing force.

Two reversible heat engines operate in series between a source at 527 celsius and a sink at 17 celsius deg. If the engines have equal efficiencies and the first rejects 400 kJ to the second, calculate:
(1) the temperature at which heat is supplied to the second engine
(2) the heat taken from the source
(3) the work done by each engine

Assume that the each engine operates on the carnot cycle.

A vessel of 3 m^3 capacity contains a mixture of nitrogen and carbon dioxide , the analysis by volume showing equal quantities of each. The temperature ia 15'C and the total pressure is 3.5 bar. Determine the mass of each constituent.

if a man who has a mass of 75kg climbs up a mast 32m, calculate the increase in his potential energy in reaching the top. express your answer in kJ to two sig fig and take the acceleration due to gravity to be g=9.8m s^-2

Two struts (strut-1 and strut-2) have the same length L and the same end support conditions. The modulus of elasticity E1 for strut-1 is twice the modulus of elasticity E2 for strut-2. The moment of inertia I2 for strut-2 is twice the moment of inertia I1 for strut-1. If P1 and P2 are the critical buckling loads for strut-1 and strut-2, respectively, how are P1 and P2 related?

A goods train’s diesel develops 1500kW at the driving wheels when the train is travelling at 80km/h. The driving wheels have a diameter of 1.1m. Assuming there is no slip between wheels and rail calculate the torque at the wheels and the work done by the wheels in 1 kilometre?
A. 422Nm, 987.9kJ B. 808Nm, 288MJ C. 1728Nm, 76.5kJ
D. 37125Nm, 76.5MJ E. 9842 Nm, 153MJ

What is the critical load for a strut of length 4.0 m and flexural rigidity 28 MPa if
both ends are fixed?
A. 80.80 MN B. 79 14 MN C. 69.10 MN D. 88.90 MN E. None of the above

A word 'papagay' is formed by letters of an alphabetic section. then, cards with letters are well mixed and any four of them are drawn one after another in succession and arranged in a row. what is the probability of obtaining the word 'papa' by this procedure?