# Important Questions in ME2302 - DYNAMICS OF MACHINERY ME2302 ME 2302 subject for NOV/DEC 2011 ANNA UNIVERSITY EXAMINATIONS FOR III YEAR MECH Students

**Important Possible Questions in**

__ME2302 - DYNAMICS OF MACHINERY__**ME2302**

**ME 2302**

**subject for NOV/DEC 2011 ANNA UNIVERSITY EXAMINATIONS FOR III YEAR MECH Students**

__ME2302 - DYNAMICS OF MACHINERY__**QUESTION BANK**

**PART – A (2 Marks Questions)**

- Why is flywheel necessary in a punching press?
- Define crank effort and crank pin effort.
- Distinguish between the unbalanced force caused due to rotating and reciprocating masses.
- State and explain the principle of superposition.
- When the crank is at the inner dead center, in a horizontal reciprocating steam engine, then the velocity of the piston will be ______________(zero / minimum / maximum).
- Define co-efficient of fluctuation in speed for a flywheel.
- Find the work done per cycle for an engine whose torque curve is given by T = (25000 + 5000 sin 2Î¸ – 10000 cos 2Î¸) Nm.
- Why are the cranks of a locomotive, with two cylinders, placed at 90° to each other?
- Sketch the Time Vs Displacement plot for under damped and over damped systems.
- Define logarithmic decrement.
- What type of motion is exhibited by a vibrating system when it is critically damped?
- Define Dynamic magnifier.
- The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. What will be the effect of gyroscopic couple on the aeroplane?
- When is a governor said to be ‘hunt’?
- Define D’Alembert’s principle.
- What is meant by balancing of rotating masses?
- Define the term swaying couple.
- What is meant by degrees of freedom in a vibrating system?
- Define critical speed.
- Define Magnification factor.
- Explain the term ‘vibration isolation’.
- Write a note on ‘Hunting of Governors’.
- Write the expression for Gyroscopic Couple.
- Define angular velocity of precession.
- Why single cylinder needs large size flywheel?
- Mention any two methods to avoid derailment of the locomotive.
- Compare the magnitude and direction of the unbalanced forces in the case of rotating masses and reciprocating masses.
- What is the angle between excitation frequency and actual frequency at resonance?
- Give an expression for inertia and damping force.
- What is the role of transmission ratio?
- Give an application of critical damping.
- Define the meaning of stability of a governor.
- Which part of the automobile is subjected to the gyroscopic couple?

**PART – B (16 Marks Questions)**

^{2}. If the modulus of elasticity of the shaft material is 0.83 x 10

^{11}N/m

^{2}, find the natural frequency of torsional oscillations, neglecting the inertia effect of the shaft. (AU, NOV 06)

^{th}of the impresses force. The machine crank shaft rotates at 800 rpm.

^{2}and below the piston is 1.5 kN/m

^{2}. Calculate

_{1}, m

_{2}, m

_{3}and m

_{4}attached to a rotating shaft on the same plane are 200 kg, 300 kg, 240 kg and 260 kg respectively. The corresponding radii of rotation are 0.2 m, 0.15 m, 0.25 m and 0.3 m respectively and the angles between successive masses are 45°, 75° and 135°. Find the position and magnitude of the balance mass required, if the radius of rotation is 0.2 m.

^{2}. Determine the frequency of longitudinal and transverse vibrations of the shaft.

^{2}. (AU, NOV 07)

^{2}. Is mounted on shaft A at a distance of 0.9 m from the gears. The shaft B also carries a flywheel of mass moment of inertia 16 kg-m

^{2}at a distance of 0.6 m from the gears. Neglecting the effect of the shaft and gear masses, calculate the fundamental frequency of free torsional oscillations and the positions of node. Assume modulus of rigidity as 84 GN/m

^{2}.

*F*cos Ï‰t. Determine the frequency at which resonance will occur and the maximum allowable value of

*F*if the amplitude at resonance is restricted to 5 mm.

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