Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 11 (Q.No. 16)
16.
If the diameter of a shaft subjected to torque alone, is doubled, then the horse power P can be increased to
16 P
8 P
4 P
2 P
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
2 comments Page 1 of 1.

Rahul verma said:   3 years ago
Shear stress = 16T/π*D^3.
So,
T IS PROPORTIONAL TO D^3.
POWER=2*pi*NT/60.

OVERALL.
POWER IS PROPORTIONAL TO T AND T IS PROPORTIONAL TO D^3.

So, POWER IS ALSO PROPORTIONAL TO D^3,
HERE.
D'=2D.
So,
P'=8P.
(1)

Keyur patel said:   7 years ago
Power = Torque * Rotational Speed.

When diameter is double, then torque carrying capacity become 8 times the original, so power also increase 8 times.

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