## Theory of Machine Lower pairs are those which have

Elements of pairs not held together mechanically
Surface contact between the two elements when in motion
Two elements that permit relative motion
Point or line contact between the two elements when in motion

## Theory of Machine The ratio of maximum fluctuation of energy to the work-done per cycle is called

Maximum fluctuation of energy
Fluctuation of energy
Coefficient of fluctuation of energy
None of these

## Theory of Machine When the addenda on pinion and wheel is such that the path of approach and path of recess are half of their maximum possible values, then the length of the path of contact is given by (where r = Pitch circle radius of pinion, R = Pitch circle radius of wheel, and φ = Pressure angle)

[(r + R) sinφ]/2
[(r + R) cosφ]/2
[(r² + R²) sinφ]/2
[(r² + R²) cosφ]/2

## Theory of Machine The velocity of any point in mechanism relative to any other point on the mechanism on velocity polygon is represented by the line

Not possible to determine with these data
Joining the corresponding points
At 45° to line as per (A)
Perpendicular to line as per (A)

## Theory of Machine When a slider moves on a fixed link having curved surface, their instantaneous centre lies

On their point of contact
At the centre of circle
At the pin joint
At the centre of curvature

## Theory of Machine In a rigid link OA, velocity of 'A' w.r.t. 'O' will be

At 45° to OA
Along AO
Parallel to OA
Perpendicular to OA