Question

The unit of torque is:
A. $N/m$
B. $Nm$
C. $N/{m^2}$
D. $N{m^2}$

Answer 1

Hint:The torque is the rotational effect developed by force acting on the body. It is the tendency of a force to rotate a body about an axis. The torque about a point is equal to the force and the perpendicular distance between the point of application of force and the axis of rotation. Thus, using the formula of torque, we can find out the correct answer.

Complete answer:
From the given options, we know that the units are in the SI system. Torque about a point can be expressed as:
\[Torque = Force \times Perpendicular\,distance\].
We know that the unit of the force is Newton (N) and the unit of the perpendicular distance is meter (m). Now we substitute the units in the above equation, we have,
Unit of torque $ = N \times m$
Thus, the unit of the torque is $Nm$ .

Hence, option B is the correct option.

Note:Unit is an internationally accepted reference standard in terms of which any given quantity can be measured. For example: The unit of mass is kilogram, the unit of length is meter and the unit of time is second.
Scientific measurement of any physical quantity requires:
(i) The unit in which the quantity is measured.
(ii) The magnitude or numerical value of the quantity.
For example, the length of a rod is$10\;{\text{cm}}$. Here, 10 is the numerical value and cm is the unit. It also shows a comparison that the pen is 10 times $1\;{\text{cm}}$ (standard unit).