Question

The ratio of the torsional moments of resistance of a solid circular shaft of diameter D, and a hollow circular shaft having external diameter D and internal diameter 'd' is given by

• A. $\frac{D^4}{D^4-d^4}$
• B. $\frac{D^4-d^4}{D^4}$
• C. $\frac{D^3-d^3}{D^3}$
• D. $\frac{D^3}{D^3-d^3}$

Answer 1

The correct option is A $\frac{D^4}{D^4-d^4}$

Torsional moment of resistance

$=f_s\times \left(\frac{\pi D^3}{16}\right)forsolidshaft$

$=f_s\times \left[\frac{\pi (D^4-d^4)}{16D}\right]forhollowshaft$

$\therefore$ Ratio of torsional moment of resistance

$=\frac{D^4}{(D^4-d^4)}$