Theory of Machines – Section 1

11. The pair is known as a higher pair when the relative motion between the elements of a pair is

A. turning only
B. sliding only
C. rolling only
D. partly turning and partly sliding

Correct Answer: D. partly turning and partly sliding

12. When the connection between the two elements is such that only required kind of relative motion occurs, it is known as a self-closed pair.

A. Right
B. Wrong

13. The Whitworth quick return motion mechanism is formed in a slider crank chain when the

C. slider is a fixed link

14. The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is

A. 0° and 90°
B. 0° and 180°
C. 90° and 180°
D. 180° and 360°

Correct Answer: B. 0° and 180°

15. The acceleration of the particle moving with simple harmonic motion is inversely proportional to the displacement of the particle from the mean position.

A. Yes
B. No

16. In the vibration isolation system, the transmissibility will be equal to unity, for all values of the damping factor, if ω/ωn is

17. The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω1 rad/s in the clockwise direction and the link OB turns with angular velocity ω2 rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)

A. ω12.r
B. ( ω1 – ω2)r
C. ( ω1 + ω2)r
D. ( ω1 – ω2)2r

Correct Answer: B. ( ω1 – ω2)r

18. If ω/ωn = √2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will the

A. 0.5
B. 1
C. 1.5
D. 2

19. A disturbing mass m1 attached to the rotating shaft may be balanced by a single mass m2 attached in the same plane of rotation as that of m1, such that (where r1 and r2 are the radii of rotation of m1
and m2 respectively)

A. m1r2 = m2r1
B. m1r1 = m2r2
C. m1m2 = r1r2
D. none of these

Correct Answer: B. m1r1 = m2r2

20. In railway axle boxes, the bearing used is

A. deep groove ball bearing
B. double row self-aligning ball bearing
C. double row spherical roller bearing
D. cylindrical roller bearing

Correct Answer: C. double row spherical roller bearing