Correct Answer : Option (C) : 5.1
Explanation : Force required for raising at longer end is found by F ₂xl₂ =F₁ xl₁. Reaction at fulcrum is √ (F₁²+F₂²) as the two forces are perpendicular.
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.