Correct Answer : Option (D) : √ (σ₲- σâ‚σ₂ +σ₂²)
Explanation : S(yt)=√[(σâ‚ -σâ‚‚)²+(σâ‚‚ -σ₃)²+(σ₃ -σâ‚)²]/2, for σ₃=0; expression a is obtained.
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.