Question

why anti clock wise torque is taken as positive??​

Answer 1

Answer:

In physics, the counterclockwise direction is defined as positive and clockwise is negative for rotational variables. ... For example, a torque that rotates an object counterclockwise is a positive torque (see figure 6 below). Figure 6. An applied force that causes a positive counterclockwise torque.

Answer 2

Explanation:

It is just a sign convention you can use your own but I will show you some logic.

Just use your right hand thumb rule.

In the above figure torque is applied in anti clockwise direction and if you curl your fingers in that direction your right thumb seems to be like a tensile force and you know that it will elongate the body.

Hope you will understand the logic.