Machine Kinematics Questions and Answers – Linear Velocity

1 The relative velocity of B with respect to A in a rigid link AB is

A parallel to AB

B perpendicular to AB

C along AB

D at 45°

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Answer: perpendicular to AB

2 The magnitude of linear velocity of a point B on a link AB relative to point A is

A ω x AB

B ω(AB)²

C ω²AB

D (ω x AB)²

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Answer: ω x AB

3 The direction of linear velocity of any point on a link with respect to another point on the same link is

A parallel to the link joining the points

B perpendicular to the link joining the points

C at 45° to the link joining the points

D none of the mentioned

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Answer: perpendicular to the link joining the points

4 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 anti-clockwise direction, then the rubbing velocity at the pin joint O is

A ω₁.ω₂.r

B (ω₁-ω₂)r

C (ω₁+ω₂)r

D (ω₁-ω₂)2r

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Answer: (ω₁+ω₂)r

5 In the above question, if both the links OA and OB turns in clockwise direction, then the rubbing velocity at the pin joint O is

A ω₁.ω₂.r

B (ω₁-ω₂)r

C (ω₁+ω₂)r

D (ω₁-ω₂)2r

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Answer: (ω₁-ω₂)r

6 ABCD is a four bar mechanism in which AB = 310mm and CD = 450mm. AB and CD are both perpendicular to the fixed link AD. If the velocity of B at this condition is v. Then the velocity of C is

A v

B 2/3 v

C 3/2 v

D 9/4 v

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Answer: 3/2 v

7 A thin circular disc is rolling with a uniform linear speed, along a straight path on a plane surface. Which of the following statement is correct in this regard?

A All points of the disc have the same velocity.

B The centre of the disc has zero acceleration.

C The centre of the disc has centrifugal acceleration.

D The point on the disc making contact with the plane surface has zero acceleration.

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