## Theory of Machine The unbalanced primary forces in a reciprocating engine are

Not balanced
Balanced partially
Balanced by secondary forces
Balanced completely

## Theory of Machine The secondary 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 sinθ
m.ω².r cosθ
m.ω².r (cos 2θ/n)

Zero
None of these
Minimum
Maximum

## Theory of Machine Which of the following is a turning pair?

Ball and a socket joint
Shaft with collars at both ends fitted into a circular hole
Lead screw of a lathe with nut
Piston and cylinder of a reciprocating steam engine

Fc = ar
Fc = a/r + b
Fc = ar - b
Fc = ar + b

## Theory of Machine Oldham’s coupling is an inversion of the kinematic chain used in

Elliptical trammels
Rotary engine
Whitworth quick return mechanism
Universal joint