Mechanical Engineering Answers

A Single cylinder double acting steam engine develops 150 kw at a mean speed of 80 rpm. The co-efficient of fluctuation of energy is 0.1 and fluctuation of speed is 2% of the mean speed. If the diameter of the flywheel rim is 2 meters and the hub and spokes provided 5% of the rotational inertia of the flywheel. Find the mass and cross sectional area of the flywheel rim. Assume density of flywheel as 7200 kg/m3.

The crank and connecting rod of a steam engine are 0.3 m and 1.5 m in length. The crank rotates at 180 rpm. Clock wise. Determine the velocity and acceleration of the piston when the crank is at 40 degrees from the inner dead centre position. Also determine the position of the crank for zero acceleration of the piston.

1. A gun barrel of mass 600 kg has a recoil spring of stiffness 294 kN/meter. If the barrel recoils 1.3 m on firing determine (i) the initial recoil velocity of the barrel (ii) the critical damping co-efficient of the dash pot which is engaged at the end of the recoil stroke (iii) the equation of motion of the gun barrel if the time of recoil is of time period.

Oil, with 900 kg/m3 and 0.00001 m2/s, flows at 0.2 m3/s through 500 m of 200-mm diameter
cast iron pipe. Determine the head loss.

A body weighs 1000 lbf when exposed to a standard earth gravity g = 32.174 ft/s2. (a) What
is its mass in kg? (b) What will the weight of this body be in N if it is exposed to the
moon’s standard acceleration gmoon = 1.62 m/s2?

It is desired to transmit 90 kW by means of a solid circular shaft roating at 3.5 rad/s. the allowable shearing stress it 45 MPa. Find the required shaft diameter.

A cooper tube 55 mm in outside diameter and of will thickness 5 mm fits loosely over a solid steel circular bar 40 mm in diameter. The two members are fastened together by two metal pins each 8 mm in diameter and passing transversely through both members, one pin being near each and of the assembly. At room temperature the assembly is just stress free when the pins are in position. The temperature of the entire assembly is then raised 40°C. Calculate the average shear stress in the pins. For cooper E=90GPa, a=18x10¯6/°C;for steel E=200GPa, a=12x10¯6/°C.

A plane element is subject to the stresses o,x= 60 MPa, y= -60 MPa, and txy = 0. Determine analytically the maximum shearing stress existing in the element. What is the direction of the planes on which the maximum shearing stresses occur?

A plane element is subject to the stresses x= 50 MPa ard y=-50 MPa.From Mohr's cirele determine the stresses acting on a plane inc lined at 20 to the -axis.

A man of mass 80 kg is travelling in a lift which is moving upwards. If the lift
comes to rest from a velocity of 2 m/s in a 2 seconds, find the force exerted by the
man on the lift floor if the deceleration is constant. What would be the reaction if the
lift were travelling downwards?