Question:

If force [F], acceleration [A] and time [T] are chosen as the fundamental physical quantities. Find the dimensions of energy

Updated On: Nov 13, 2025
  • [F] [A−1] [T]

  • [F] [A] [T]

  • [F] [A] [T2]

  • [F] [A] [T−1]

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The Correct Option is C

Solution and Explanation

To find the dimensions of energy using the given fundamental physical quantities: Force [F], Acceleration [A], and Time [T], we need to express energy in terms of these quantities. 

Energy is typically defined as work done, which can be calculated using the formula:

\(\text{Energy} (E) = \text{Force} (F) \times \text{Distance} (d)\)

We know that:

  • Force \([F]\) is already given as a fundamental quantity.
  • Distance can be expressed as the product of Velocity and Time: \(d = v \times t\)

Also, Velocity \(v\) can be expressed in terms of Acceleration and Time:

\(v = A \times T\)

Substituting this into the distance formula:

\(d = (A \times T) \times T = A \times T^2\)

Thus, Energy becomes:

\(E = F \times d = F \times (A \times T^2) = F \times A \times T^2\)

Therefore, the dimensions of energy in terms of [F], [A], and [T] are:

\([F] [A] [T^2]\)

This matches the provided correct answer option: [F] [A] [T2].

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Concepts Used:

Dimensional Analysis

Dimensional Analysis is a process which helps verify any formula by the using the principle of homogeneity. Basically dimensions of each term of a dimensional equation on both sides should be the same. 

Limitation of Dimensional Analysis: Dimensional analysis does not check for the correctness of value of constants in an equation.
 

Using Dimensional Analysis to check the correctness of the equation

Let us understand this with an example:

Suppose we don’t know the correct formula relation between speed, distance and time,

We don’t know whether 

(i) Speed = Distance/Time is correct or

(ii) Speed =Time/Distance.

Now, we can use dimensional analysis to check whether this equation is correct or not.

By reducing both sides of the equation in its fundamental units form, we get

(i) [L][T]-¹ = [L] / [T] (Right)

(ii) [L][T]-¹ = [T] / [L] (Wrong)

From the above example it is evident that the dimensional formula establishes the correctness of an equation.