## Theory of Machine Kinematic pairs are those which have two elements that

Have surface contact
Are held together
Have line contact
Permit relative motion

Closed pair
Mechanical pair
Rolling pair
Open pair

## Theory of Machine The contact ratio is given by

(Length of the arc of approach)/cosφ
(Length of path of recess)/(Circular pitch)
(Length of the path of approach)/(Circular pitch)
(Length of the arc of contact)/(Circular pitch)

## Theory of Machine Hammer blow

Varies as the square root of the speed
Varies inversely with the square of the speed
Is the maximum horizontal unbalanced force caused by the mass provided to balance the reciprocating masses.
Is the maximum vertical unbalanced force caused by the mass added to balance the reciprocating masses

## Theory of Machine The frictional torque transmitted in a flat collar bearing, considering uniform pressure, is (where r₁ and r₂ = External and internal radii of collar respectively)

(2/3). μ W (r₁ + r₂)
(1/2). μ W (r₁ + r₂)
(1/2). μ W [(r₁³ - r₂³)/(r₁² - r₂²)]
(2/3). μ W [(r₁³ - r₂³)/(r₁² - r₂²)]

## Theory of Machine Oldham's coupling is the

Second inversion of double slider crank chain
Third inversion of double slider crank chain
Third inversion of slider crank chain
Second inversion of single slider crank chain