Question

If the diameter of a shaft subjected to torque alone, is doubled, then the horse power P can be increased to

• A. 16P
• B. 8P
• C. 4P
• D. 2P

Answer 1

The correct option is B 8P

Torsion formula is given as

$\frac{T}{J}=\frac{G\theta }{L}=\frac{\tau }{r}$

Power = Torque $\times$ Rotational speed $=T\omega$
When diameter is doubled, the torque carrying capacity becomes 8 times the original. So power also increases 8 times.