## Theory of Machine In a four-bar chain it is required to give an oscillatory motion to the follower for a continuous rotation of the crank. For the lengths of 50 mm of crank and 70 mm of the follower, determine theoretical maximum length of coupler. The distance between fixed pivots of crank and followers is

45 mm
Slightly less than 95 mm
Slightly more than 95 mm
95 mm

## Theory of Machine A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will

Become equal to 2R
Become equal to R/2
Remain same as before
Become equal to R/4

ω₁.ω₂.r
(ω₁ + ω₂) r
(ω₁ - ω₂) 2r
(ω₁ - ω₂) r

(ω₁ - ω₂)r
(ω₁ + ω₂)r
(ω₁ - ω₂)2r
ω₁.ω₂.r

## Theory of Machine The primary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, θ = Angle of inclination of crank with the line of stroke, and n = Ratio of the length of connecting rod to radius of crank)

m.ω².r (sin 2θ/n)
m.ω².r cosθ
m.ω².r (cos 2θ/n)
m.ω².r sinθ