Theory of Machine
The equation of motion for a vibrating system with viscous damping is (d²x/dt²) + (c/m).(dx/dt) + (s/m).x = 0, if the roots of the equation are __________ then the system will be under damped.

None of these
Real
Complex conjugate
Equal

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Theory of Machine
Two heavy rotating masses are connected by shafts of lengths l₁, l₂ and l₃ and the corresponding diameters are d₁, d₂ and d₃. This system is reduced to a torsionally equivalent system having uniform diameter d = d₁ of the shaft. The equivalent length of the shaft is

(l₁ + l₂ + l₃)/3
l = l₁ + l₂.(d₁/d₂)⁴ + l₃.(d₁/d₃)⁴
l₁ + l₂ + l₃
l = l₁ + l₂.(d₁/d₂)³ + l₂.(d₁/d₃)³

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

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Theory of Machine
Which of the following statements regarding laws governing the friction between dry surfaces are correct?

The friction force is independent of me area of contact.
The friction force is dependent on the materials of the contact surfaces.
The friction force is directly proportional to the normal force.
All of these

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Theory of Machine
Crowning on pulleys helps

In decreasing the slip of the belt
Increase belt and pulley life
In increasing velocity ratio
For automatic adjustment of belt position so that belt runs centrally

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