Question

For a hollow shaft of external and internal diameters 10 cm and 5 cm respectively, the torsional sectional modulus will be approximately

Answer 1

the ans is 184.08 cubic cm

Answer 2

Given:  

A hollow shaft internal diameter  5 cm and external diameter 10 cm

To Find:

Torsional Section Modulus of hollow shaft

Solution:

Section Modulus of a shaft-  section modulus of a body is defined as the ratio of total area moment of Inertia and the distance of extreme fibre.

$Z =\frac{I}{y}$

I = area moment of Inertia

y = extreme fibre position

 Section modulus of a hollow shaft

I of hollow shaft = $\frac{\pi(D^{4}- d^{4} ) }{32}$

y = $\frac{D}{2}$

y = 5 cm

$I =\frac{\pi(10^{4}-5^{4} ) }{32} ;\\I= 920 cm^{4}$

$Z = \frac{920}{5}\\ \\Z = 184 cm^{3}$

The section modulus of the above hollow shaft is 184$cm^{3}$