Question

A flexible shaft consists of a 3 mm diameter steel wire in a flexible hollow tube which imposes a frictional torque of 0.04 N m per meter when the shaft rotates. The shaft is to be used for applying a torque of 0.1 N m to actuate a switch. What is the maximum length of shaft that may be used if the shear stress in the shaft is not to exceed 50 MPa?

Answer 1

2.5m

Step-by-step explanation:

Torque is defined as the rotational effect of a force on a body.

The torque T for the maximum shear stress is given as 0.1 Nm

Frictional torque is the torque caused by a frictional force

The frictional torque F is given as 0.04 Nm/m

The maximum length of the shaft is thus given as

L = T / F

= 0.1/0.04

L= 2.5 m