Freshers Mechanical Engineers Interview Questions & Answers
1. Define primary and secondary transducers ?
Ans: A primary transducer senses a physical phenomena and converts it to an analogous output.
The analogous output is then converted into an electrical signal by secondary transducer.
2. How many links and turning pairs are required (minimum) for a kinematic chain ? How many will be instantaneous centres for such a chain ?
Ans: 4 links and 4 turning pairs. Six instantaneous centres.
3. When does a kinematic chain become a kinematic mechanism ?
Ans: When any one link is fixed.
4. When Coriolis component is encountered ?
Ans: When a point moves along a path that has rotational motion.
5. Where the pitch point on a cam located ?
Ans: It is the point on cam pitch curve having the maximum pressure angle.
6. What is the basic circle of a cam profile ?
Ans: It is the minimum radius circle drawn to the cam profile.
7. If the ratio of tight side to slack side tension on belt drive is increaseed by %, how much power transmission will increase ?
Ans: By %.
8. What is the effect of creep of belt in belt drive ?
Ans: It decreases speed of driven pully and the power output.
9. What is the difference between kinetics and kinematics ?
Ans: While kinematics studies the motion of a body without regard to the mass of body and forces acting on it, kinetics does not consider mass or forces.
10. What is the difference between couple and angular momentum and how they are related ?
Ans: Couple is product of moment of inertia and angular acceleration. Angular momentum is the product of moment of inertia and angular speed. Time rate of change of angular momentum of body is equal to external couple acting on the body.
11. What is the difference between simple and compound machine ?
Ans: In simple machine there is one point each for effort and load but in compound machine there are more than one point for application of load and effort.
12. What is the difference between mechanical advantage and velocity ratio ?
Ans: Mechanical advantage is the ratio of load lifted and the effort applied. Velocity ratio is the ratio between the distance moved by the effort applied and the distance moved by the load lifted.
13. Explain the difference between elastic collision and inelastic collision ?
Ans: In elastic collision, the total momentum and total kinetic energy remains constant before and afater the collision. In inelastic collision the total momentum remains constant but the total kinetic energy remains same before and after the collision.
14. What type of gears will you recommend for non-parallel intersecting shafts and non-parallel non-intersecting shafts ?
Ans: Bevel gears, and cross-helical gears respectively.
15. In a vibrating system with single degree of freedom how undamped frequency is related to natural frequency ?
Ans: Former is greater.
16. Differentiate between elastic collision, inelastic collision, and completely inelastic collision.
Ans: In elastic collision both total momentum and kinetic energy is conserved in collision but in inelastic collision the total momentum is conserved and K.E. is not. In completely inelastic collision the two colliding bodies stick together.
17. Give example of rigid link and flexible link ?
Ans: Connecting rod and belt respectively.
18. What is the difference between higher pair and lower pair ?
Ans: Higher pair has point or line contact between two links and lower pair has surface contact between two links while in motion.
19. Which mechanism gives approximate straight line motion and which one accurate straight line motion ?
Ans: Watt, Scott-Russel respectively.
20. What are seismic instruments ?
Ans: Seismic instruments are absolute motion measurement devices to indicate or record absolute displacement, velocity and acceleration of a vibrating body.
21. Which type of cam would you recommend for obtaining constant acceleration ?
Ans: Parabola cam.
22. A fixed gear having teeth meshes with another gear having 20 teeth form¬ing epicyclic gear train. Centre lines of both gears are joined by an arm. How many rotations small gear will make for one rotation of arm ?
Ans: /20 + 1 = 16.
23. Whether Whitworth quick return mechanism is an inversion of double slider crank mechanism ?
Ans: No.
24. Whether the sensitivity of isochronous governor is zero or infinity ?
Ans: Zero.
25. On what factors depends the critical damping ?
Ans: It depends on mass and stiffness.