The dimensions of stress are:

Asked in NEET 2020 · Dimensional formula of a named quantity

Answer: (3) [ML⁻¹T⁻²]

Step-by-step solution

Idea: stress is the internal restoring force per unit area of cross-section.

stress=F/A

[F]=[MLT⁻²] and [A]=[L²]

[stress]=([MLT⁻²])/([L²])=[ML⁻¹T⁻²]

These are also the dimensions of pressure and of Young's modulus.

(1) comes from these are the dimensions of energy or torque; stress is a force per unit area, not a force times a length
(2) comes from dividing the force by a length instead of by an area, and then cancelling the length exponent to zero
(4) comes from these are the dimensions of force itself, with the division by area left out

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