List of top Mechanical Engineering Questions

Which of the following strain mainly represents the change of shape?
A steel rod of diameter 10 mm and 1 m long is heated from 20°C to 120°C, its coefficient of thermal expansion \( \alpha = 12 \times 10^{-6} / \text{K} \) and Young’s Modulus \( E = 200 \, \text{GPa} \). If the rod is free to expand, the thermal stress developed in it is

A solid cylinder of weight \( W = 100 \, \text{N} \) and radius \( r = 0.5 \, \text{m} \) is pulled along a horizontal plane by a horizontal force \( P = 90 \, \text{N} \) applied to the end of the string wound around the cylinder. What is the angular acceleration of the disc? Assume \( g = 10 \, \text{m/s}^2 \).

In the system of pulleys shown in Figure, the pulleys are massless and the strings are inextensible. What is the relation between the accelerations of blocks \( A \) and \( B \)?

A plane truss has four members and four joints. The truss is
A 160 g cricket ball is moving with a speed of 20 m/s. What force is required to stop the ball in 0.2 seconds?
Which of the following forces are considered in the equations of virtual work?
If the acceleration-time diagram is represented by a horizontal straight line, then the displacement is:
"The moment of resultant of all the forces in a plane about any point is equal to the algebraic sum of moment of all the forces about the same point". This statement is known as

The force acting at a point \( A \) is shown in the figure. The equivalent force system acting at point \( B \) is:

A uniform rod AB is in equilibrium when resting on a smooth groove, the walls of which are at right angles to each other as shown in the figure. What is the relation between \( \theta \) and \( \phi \) in degrees?

An intermediate shaft of a gearbox, supporting two spur gears A and B and mounted between two bearings C1 and C2, is shown in the below figure. The pitch circle diameters of gears A and B are 500 and 250 mm respectively. The shaft is made of alloy steel 20MnCr5. (\( S_{ut} = 620 \) and \( S_{yt} = 480 \) N/mm\(^2\)). The factors \( k_b \) and \( k_t \) of the ASME code are 2 and 1.5 respectively. The gears are keyed to the shaft. Determine the shaft diameter using the ASME code. 
Intermediate shaft of a gearbox
If Stanton number is 0.5, Reynolds number is 39 and Nusselt number is 390, then the Prandtl number is:
According to ——––––––––– equation “for most metals, yield strength depends on average grain diameter.”
Which of the statements is not true for Bainite, which is a micro constituent in Iron–Carbon Alloys?
Having a eutectoid composition ——––––––––– is a microstructural product of an iron–carbon alloy consisting of alternating layers of ferrite and cementite.
What structure is formed in the heat affected zone of a medium carbon steel weld due to rapid cooling?
Air enters the compressor at 100 kPa and 25°C having the volume of 1.8 m3/kg and compressed to 5 bar isothermally. The change in internal energy during the process is
A riveting machine is driven by a constant torque 3 kW motor. The moving parts including the flywheel are equivalent to 150 kg at 0.6 m radius. One riveting operation takes 1 second and absorbs 10000 N-m of energy. The speed of the flywheel is 300 r.p.m. before riveting. Find the speed immediately after riveting. How many rivets can be closed per minute?
The following equation is equal to the value of \[ \left( \frac{\partial T}{\partial V} \right)_P \left( \frac{\partial V}{\partial T} \right)_P \left( \frac{\partial P}{\partial V} \right)_T = ? \]
The first moment of area of a semicircular area about its diameter ‘d’ is given by:
Identify the operation related to drilling which is illustrated in Figure below.
operation related to drilling
Identify the operation which cannot be performed using a conventional lathe.
A beam with a span of 4.5 meters carries a point load of 30 kN at 3 meters from the left support. If for the section, \( I_{xx} = 54.97 \times 10^{-6} \) m\(^4\) and \( E = 200 \) GN/m\(^2\), then the deflection under the load is:
A wire of length L and radius r is rigidly clamped from one end and the other end is pulled by force F. It is found that the wire elongates by 5 cm. Another wire of the same material but 4L length and 4r radius is pulled by 4F force under identical conditions. What will be the final elongation of the wire?