Theory of Machine The efficiency of a screw jack is maximum, when (where α = Helix angle, and φ = Angle of friction) α = 45° + φ/2 α = 90° + φ α = 45° - φ/2 α = 90° - φ α = 45° + φ/2 α = 90° + φ α = 45° - φ/2 α = 90° - φ ANSWER DOWNLOAD EXAMIANS APP
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 l₁ + l₂ + l₃ l = l₁ + l₂.(d₁/d₂)³ + l₂.(d₁/d₃)³ (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 (l₁ + l₂ + l₃)/3 ANSWER DOWNLOAD EXAMIANS APP
Theory of Machine In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be (where ω = Angular speed of the system, ωn = Natural frequency of vibration of the system) Less than unity Greater than unity Zero Equal to unity Less than unity Greater than unity Zero Equal to unity ANSWER DOWNLOAD EXAMIANS APP
Theory of Machine The natural frequency of free transverse vibrations due to a point load acting over a simply supported shaft is equal to (where δ = Static deflection of a simply supported shaft due to the point load) 0.6253/√δ 0.571/√δ 0.4985/√δ 0.5615/√δ 0.6253/√δ 0.571/√δ 0.4985/√δ 0.5615/√δ ANSWER DOWNLOAD EXAMIANS APP
Theory of Machine In a screw jack, the effort required to lift the load W is given by (where α = Helix angle, and φ = Angle of friction) P = W tan(α + φ) P = W tan(α - φ) P = W cos(α + φ) P = W tan(φ - α) P = W tan(α + φ) P = W tan(α - φ) P = W cos(α + φ) P = W tan(φ - α) ANSWER DOWNLOAD EXAMIANS APP
Theory of Machine A system in dynamic balance implies that The system is also statically balanced There is no critical speed in the system The system is critically damped There will absolutely no wear of bearings The system is also statically balanced There is no critical speed in the system The system is critically damped There will absolutely no wear of bearings ANSWER DOWNLOAD EXAMIANS APP
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