1. In S.I system, unit of stress is:
A. [latex]\frac{kg}{{cm}^{2}}[/latex]
B. N
C. [latex]\frac{N}{{m}^{2}}[/latex]
D. Watt
Answer - Option C
Explanation -
The S.I. unit of stress is [latex]\frac{N}{{m}^{2}}[/latex].
2. What is the function of push rod in a diesel engine? It transfers force between -
A. Cam and rocker arm
B. Connecting rod and piston
C. Crankshaft and piston
D. None of these
Answer - Option A
Explanation -
A push rod is a component of the valve train of certain piston engines. It's function is essentially to push the valve open. Rods used in an overhead valve engine to open and close the valves. One end is pushed up by the cam and other end makes contact with the rocker arms which rotates and pushes the valve open.
3. . In C.G.S system, the unit of strain is:
A. [latex]\frac{cm}{kg}[/latex]
B. [latex]\frac{m}{kg}[/latex]
C. no units
D. None of these
Answer - Option C
Explanation -
Strain is unit less quantity. It is dimensionless.
4. In the case of a uniformly distributed load on a simply supported beam, the bending moment
diagram would be-
Answer - Option B
Explanation -
Simply supported beam with udl,
Now FBD, take sagging (+ve) and hogging (– ve),
Now, [latex]{M}_{x} = \frac{\omega l}{2}x - \omega x \frac{x}{2}[/latex]
[latex]{M}_{x} = \frac{\omega l}{2}x - \omega x \frac{{x}^{2}}{2}[/latex]
[latex]{M}_{A} = ({A}^{B}x = L)[/latex]
[latex]\omega x \frac{{x}^{2}}{2} - \omega x \frac{{x}^{2}}{2} = 0[/latex]
For maximum bending
[latex]\frac{d {M}_{X}}{dx} = \frac{\omega l}{2} - \omega = 0[/latex]
Now, x = [latex]\frac{1}{2}[/latex], so bending moment at x = [latex]\frac{1}{2}[/latex] to be maximum so,
Mc = [latex]\frac{\omega l}{2} * \frac{l}{2} - \frac{\omega {(\frac{l}{2})}^{2}}{2} = \frac{\omega{l}^{2}}{4} - \frac{\omega{l}^{2}}{8} = \frac{\omega{l}^{2}}{8}[/latex]
Mc = [latex]\frac{\omega{l}^{2}}{8}[/latex]
Hence, BMD should be
So, option (b) is correct.
5. A simply supported beam carries a varying load from zero at one end to [latex]\omega[/latex] N/m at the other end (as under).
The length of the beam is L. The shear force will be zero at a distance 'x' from A. Find 'x' :
A. [latex]\frac{L}{2}[/latex]
B. [latex]\frac{L}{4}[/latex]
C. [latex]\frac{L}{\sqrt{3}}[/latex]
D. [latex]\frac{L}{3}[/latex]
Answer - Option C
Explanation -
By FBD,
Load at point C = [latex]\frac{WL}{2}[/latex]
Now, [latex]\Sigma {M}_{B} = 0[/latex]
[latex]{R}_{A} * L = \frac{WL}{2} * \frac{L}{3}[/latex]
[latex]{R}_{A} = \frac{WL}{6}[/latex]
Here, from similar [latex]\Delta[/latex] AXX and AWB,
[latex]\frac{{W}_{xx}}{W} = \frac{x}{L}\Rightarrow {W}_{xx} = \frac{{W}_{x}}{L} [/latex]
Shear force at X– X cross section,
[latex]{SF at}_{xx} = \frac{WL}{6} - \frac{1}{2} * {W}_{xx} * x [/latex]
[latex]\frac{WL}{6} - \frac{1}{2} * \frac{Wx}{L} * x[/latex]
[latex]\frac{WL}{6} - \frac{1}{2} * - \frac{W{x}^{2}}{L}[/latex]
SF at X-X section = 0 [By question]
[latex]0 = \frac{WL}{6} - \frac{W{x}^{2}}{2L}[/latex]
[latex]\frac{WL}{6} = \frac{W{x}^{2}}{2L}[/latex]
[latex]\Rightarrow {x}^{2} = \frac{2{L}^{2}}{6} = \frac{{L}^{2}}{3}[/latex]
[latex]\Rightarrow x = \frac{1}{\sqrt{3}}[/latex]
6. Which one of the following is the most significant property to be considered in the selection of material for the manufacture of locating pins and drill jig bushes used in jigs and fixtures ?
A. Wear Resistance
B. Elasticity
C. Shear Strength
D. Tensile Strength
Answer - Option D
Explanation -
Tensile strength is the criteria for selection of material in manufacturing of locating pins and jug bushes.
7. What is the main shaft of an engine that controls the movement of piston ?
A. axle
B. drive shaft
C. crank shaft
D. cam shaft
Answer - Option C
8. The component of the engine that connects the link between the small end of the connecting
rod and the piston is known as
A. Cams
B. Fly wheel
C. Gudgeon pin
D.
Answer - Option C
Explanation -
Gudgeon pin is defined as the pin which holds piston rod and connecting rod together.
9. The negative ratio of transverse to axial strain is called as
A. Young's modulus
B. Shear modulus
C. Poisson's ratio
D. Bulk modulus of elasticity
Answer - Option C
Explanation -
Poisson’s ratio: Poisson’s ratio is the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force. Tensile deformation is considered positive and compressive deformation is considered negative.
10. To connect piston to the connecting rod the_______ are used
A. rod caps
B. cap bolts
C. small end bearings
D. gudgeon pins
Answer - Option D
Explanation -
Gudgeon pins are those pins which holds piston and connecting rod together.