The efficiency of a screw jack is maximum, when(where α = Helix ang – McqOptions

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1.	The efficiency of a screw jack is maximum, when(where α = Helix angle, and φ = Angle of friction.)
A.	α = 45° + φ/2
B.	α = 45° - φ/2
C.	α = 90° + φ
D.	α = 90° - φ
Answer» C. α = 90° + φ

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