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

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

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
The static balancing is satisfactory for low speed rotors but with increasing speeds, dynamic balancing becomes necessary. This is because, the

Effects of unbalances are proportional to the square of the speed
Unbalanced forces are not dangerous at higher speeds
Effects of unbalances are directly proportional to the speed
Unbalanced couples are caused only at higher speeds

ANSWER DOWNLOAD EXAMIANS APP