# Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 8)

8.

Two shafts '

*A*' and '*B*' transmit the same power. The speed of shaft '*A*' is 250 r.p.m. and that of shaft '*B*' is 300 r.p.m. The shaft '*B*' has the greater diameter.Discussion:

52 comments Page 1 of 6.
Ram said:
5 years ago

Interms of speed, we use less diameter shafts.

(2)

Bumba said:
5 years ago

Speed is inversely proportional to the Dia of shaft.

(12)

Rajneesh singraul said:
6 years ago

Shaft rpm can not determine by diameter. It Can be determined by hollow shaft and solid shaft.

(7)

Bhargav Panchal said:
6 years ago

v = π * D * N/60.

From this v is proportional to diameter and N both. So, I think the statement is true.

From this v is proportional to diameter and N both. So, I think the statement is true.

(1)

Muswar_SIYAL said:
6 years ago

Here the term "Two shafts ' is used.

Not Two Pulleys, so that I think no relation.

Not Two Pulleys, so that I think no relation.

(2)

Harshal Dongre said:
6 years ago

P=(2*π*N*T/60).

So for same power, NT=Constant.

Therefore for less rpm more torque is transferred, so greater the torque greater is the diameter.

So for same power, NT=Constant.

Therefore for less rpm more torque is transferred, so greater the torque greater is the diameter.

(6)

BRIJ MOHAN VERMA said:
6 years ago

Diameter of a shaft in any power transmission is directly proportional to shaft speed.

(1)

Kartik Uttarkar said:
6 years ago

If the RPM is increasing then diameter value should be small but not big. And vice-versa if the RPM value is decreasing then it should have bigger diameter.

(1)

Govind kumar said:
7 years ago

If dia of shaft is small then it's rotation is more than the larger dia of shaft.

Kishan P said:
7 years ago

As Rpm increasing, torque in reduces. As torque reduce the maximum shear stress at the outer most fibre will reduce.

As it's having less shear stress, it required smaller diameter.

Hence when Rpm increasing, the diameter will be smaller When compared to a member having lower Rpm.

As it's having less shear stress, it required smaller diameter.

Hence when Rpm increasing, the diameter will be smaller When compared to a member having lower Rpm.

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