Machine Design Multiple Choice Questions on “Stresses in Rope Wires”.
1. The wire rope is subjected to
a) Tensile Stress
b) Bending Stress
c) Both bending and tensile stress
d) None of the listed
Answer: c
Clarification: There is direct tensile stress due to load being raised as well as bending stress.
2. In design of wire ropes, bending stress is converted into an equivalent bending load which is given by [d= diameter of individual wire and D= diameter of sheave].
a) AEd/D
b) 2AEd/D
c) AEd/2D
d) None of the listed
Answer: a
Clarification: P=σA and σ=Ed/D.
3. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500. Number of wire ropes can be taken 2. Calculate the weight of material raised by each load.
a) None of the listed
b) 2450N
c) 4900N
d) 9800N
Answer: b
Clarification: Weight of material raised by each rope= 4.9/2.
4. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Calculate the weight of wire if weight of 50m wire is 18kg.
a) 19.36N
b) 90.25N
c) 77.70N
d) 56.66N
Answer: c
Clarification: W=mass per unit length x length x g.
5. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the weight of wire if weight of 50m wire is 18kg. Calculate the force due to acceleration.
a) 1000N
b) 309.144N
c) 504.225N
d) 102.225N
Answer: b
Clarification: Mass of material raised by each wire rope= 2450/9.81 = 249.7kg. Mass of each wire rope= 77.7/9.81 =7.92kg. Force due to acceleration= [249.7+7.92] x 1.2.
6. An elevator is assembled to raise equipment to a height of 22m. It is estimated that maximum weight of the material to be raised is 4.9kN. It is observed acceleration in such cases is 1.2m/s².10mm diameter wire ropes with fibre core are used. The tensile designation of the wire is 1500.Number of rope wires is assumed to be 2. Number of rope wires is assumed to be 2. Calculate the total load on wire rope neglecting the bending load if weight of 50m wire is 18kg.
a) 1054.55N
b) 3504.55N
c) 2836.84N
d) 5678.6N
Answer: c
Clarification: F=4900/2 + 77.7 + 249.7×1.2 + 7.92×1.2.
7. Small sheaves are preferred over large sheaves on what parameters?
a) Increasingly centrifugal force in large sheaves
b) Higher cost of small sheaves
c) Preferring centrifugal force reduction even for more money
d) None of the listed