Machine Design Miscellaneous
 Two shafts A and B are made of the same material. The diameter of shaft B is twice that of shaft A The ratio of power which can be transmitted by shaft A to that of shaft B is

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T_{A} = π × d^{3}τ 16 T_{B} = π × (2d)^{3}τ 16 P_{A} = T_{A} = 1 P_{B} T_{B} 8 Correct Option: C
T_{A} = π × d^{3}τ 16 T_{B} = π × (2d)^{3}τ 16 P_{A} = T_{A} = 1 P_{B} T_{B} 8
 Torque to weight ratio for a circular shaft transmitting power is directly proportional to the

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T = π d^{3}τ 16 w = π d^{2} ρl 4 T ∝ d w Correct Option: B
T = π d^{3}τ 16 w = π d^{2} ρl 4 T ∝ d w
 A large uniform plate containing a rivet hole subjected to uniform uniaxial tension of 95 MPa. The maximum stress in the plate is

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Max Stress = Avg. Force Min. Area = 95 × 10 × t = 100 MPa (10  0.5)t Correct Option: A
Max Stress = Avg. Force Min. Area = 95 × 10 × t = 100 MPa (10  0.5)t
 The outside diameter of a hollow shaft that is twice its inside diameter the ratio of its torque carrying capacity to that of a solid shaft of the same material and the same outside diameter is

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T_{hollow} = π d^{4}  d^{4} 2τ ......(1) 32 16 d T_{solid} = π d^{3}τ .......(2) 16
By dividing (1) with (2)T_{hollow} = 15 T_{solid} 16 Correct Option: A
T_{hollow} = π d^{4}  d^{4} 2τ ......(1) 32 16 d T_{solid} = π d^{3}τ .......(2) 16
By dividing (1) with (2)T_{hollow} = 15 T_{solid} 16
 The expected life of a ball bearing subjected to a load of 9800 N and working at 1000 rpm is 3000 hours. What is the expected life of the same bearing for a similar load of 4900 N and speed of 2000 rpm?

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L (P)^{3} = constant
L_{1} = P_{2} ^{3} L_{2} P_{1} ⇒ 1000 × 60 × 3000 = 4900 ^{3} 2000 × 60 × t_{2} 9800
t_{2} = 12000 hours
Correct Option: B
L (P)^{3} = constant
L_{1} = P_{2} ^{3} L_{2} P_{1} ⇒ 1000 × 60 × 3000 = 4900 ^{3} 2000 × 60 × t_{2} 9800
t_{2} = 12000 hours