Correct Answer : Option (A) : Square Head
Explanation : Angle of rotation for hexagonal head is one sixth of a revolution to enable the next pair of flats to be engaged while it is one fourth of a revolution in case of square head.
Correct Answer : Drums with helical grooves
Explanation : They have more bearing surface of the drum and prevent friction between adjacent turns of the rope.
Correct Answer : Increasingly centrifugal force in large sheaves
Explanation : Larger sheaves have higher centrifugal forces and higher cost because more material is used in their construction.
Correct Answer : Both bending and tensile stress
Explanation : There is direct tensile stress due to load being raised as well as bending stress.