## Machine Design Miscellaneous

#### Machine Design

1. 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

1.  TA = π × d3τ 16

 TB = π × (2d)3τ 16

 PA = TA = 1 PB TB 8

##### Correct Option: C

 TA = π × d3τ 16

 TB = π × (2d)3τ 16

 PA = TA = 1 PB TB 8

1. Torque to weight ratio for a circular shaft transmitting power is directly proportional to the

1.  T = π d3τ 16

 w = π d2 ρl 4

 T ∝ d w

##### Correct Option: B

 T = π d3τ 16

 w = π d2 ρl 4

 T ∝ d w

1. A large uniform plate containing a rivet hole subjected to uniform uniaxial tension of 95 MPa. The maximum stress in the plate is

1.  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

1. 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

1.  Thollow = π d4 - d4 2τ ......(1) 32 16 d

 Tsolid = π d3τ .......(2) 16

By dividing (1) with (2)
 Thollow = 15 Tsolid 16

##### Correct Option: A

 Thollow = π d4 - d4 2τ ......(1) 32 16 d

 Tsolid = π d3τ .......(2) 16

By dividing (1) with (2)
 Thollow = 15 Tsolid 16

1. 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?

1. L (P)3 = constant

 L1 = P2 3 L2 P1

 ⇒ 1000 × 60 × 3000 = 4900 3 2000 × 60 × t2 9800

t2 = 12000 hours

##### Correct Option: B

L (P)3 = constant

 L1 = P2 3 L2 P1

 ⇒ 1000 × 60 × 3000 = 4900 3 2000 × 60 × t2 9800

t2 = 12000 hours