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  • Question
  • The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ?1 rad/s in the clockwise direction and the link OB turns with angular velocity ?2 rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)


  • Options
  • A. ?1.?2.r
  • B. ( ?1 - ?2)r
  • C. ( ?1 + ?2)r
  • D. ( ?1 - ?2)2r

  • Correct Answer
  • ( ?1 - ?2)r 


  • Theory of machines problems


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    • 1. In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon

    • Options
    • A. total lift, total angle of lift, minimum radius of cam and cam speed
    • B. radius of circular arc, cam speed, location of centre of circular arc and roller diameter
    • C. mass of cam follower linkage, spring stiffness and cam speed
    • D. total lift, centre of gravity of the cam and cam speed
    • Discuss
    • 2. When the connection between the two elements is such that only required kind of relative motion occurs, it is known as self-closed pair.

    • Options
    • A. Right
    • B. Wrong
    • Discuss
    • 3. In a screw jack, the effort required to lower the load W is given by

    • Options
    • A. P = W tan(? - ?)
    • B. P = W tan(? + ?)
    • C. P = W tan(? - ?)
    • D. P = W cos(? + ?)
    • Discuss
    • 4. The pair is known as a higher pair, when the relative motion between the elements of a pair is

    • Options
    • A. turning only
    • B. sliding only
    • C. rolling only
    • D. partly turning and partly sliding
    • Discuss
    • 5. The static friction

    • Options
    • A. bears a constant ratio to the normal reaction between the two surfaces
    • B. is independent of the area of contact, between the two surfaces
    • C. always acts in a direction, opposite to that in which the body tends to move
    • D. all of the above
    • Discuss
    • 6. The frequency of damped vibrations with viscous damping is __________ the frequency of undamped vibrations.

    • Options
    • A. more than
    • B. less than
    • C. same as
    • Discuss
    • 7. In order to balance the reciprocating masses,

    • Options
    • A. primary forces and couples must be balanced
    • B. secondary forces and couples must be balanced
    • C. both (a) and (b)
    • D. none of these
    • Discuss
    • 8. An automobile steering gear is an example of

    • Options
    • A. sliding pair
    • B. rolling pair
    • C. lower pair
    • D. higher pair
    • Discuss
    • 9. The dynamic friction is the friction experienced by a body, when the body

    • Options
    • A. is in motion
    • B. is at rest
    • C. just begins to slide over the surface of the other body
    • D. none of the above
    • Discuss
    • 10. Whitworth quick return motion mechanism consists of three turning pairs and one sliding pair.

    • Options
    • A. Right
    • B. Wrong
    • Discuss


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