In a screw jack, the effort required to lower 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)
Correct Answer: P = W tan (ɸ – α)
The effort required at the circumference of the screw to lower the load W is given by P = W tan (ɸ – α) The effort required at the circumference of the screw to lift the load W is given by P = W tan (α + ɸ).