In a screw jack, the effort required to lift the load W is given by
(a) P = W tan (α – ɸ)
(b) P = W tan (α + ɸ)
(c) P = W tan (ɸ – α)
(d) P = W cos (α + ɸ)
This question was posed to me in a national level competition.
The question is from Friction in Journal Bearing- Friction Circle in division Friction of Machine Kinematics