Theory of Machine
The factional torque for square thread at the mean radius r while raising load W is given by

T = W.r tanφ
T = W.r tan(φ - α)
T = W.r tan(φ + α)
T = W.r tanα

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
Higher pairs are those which have

Point or line contact between the two elements when in motion
Surface contact between the two elements when in motion
Two elements that permit relative motion
Elements of pairs not held together mechanically

ANSWER DOWNLOAD EXAMIANS APP