Verified Solution • 2025–26 Session moderate

QJEEM23Ph7acf: JEE Main 2023 Physics - Class 11 JEEM23Ph7acf Solution: If force (F), velocity (V) and time (T) are considered as…

If force (F), velocity (V) and time (T) are considered as fundamental physical quantity, then dimensional formula of density will be :

Multiple Choice Options

  • A FV−2 T2\mathrm{FV}^{-2} \mathrm{~T}^{2}
  • B FV4 T−6\mathrm{FV}^{4} \mathrm{~T}^{-6}
  • C F2 V−2 T6\mathrm{F}^{2} \mathrm{~V}^{-2} \mathrm{~T}^{6}
  • D FV−4 T−2\mathrm{FV}^{-4} \mathrm{~T}^{-2}

Step-by-Step Verified Solution

We know that force (F) has dimensions of MLT−2\mathrm{MLT}^{-2} , velocity (V) has dimensions of LT−1\mathrm{LT}^{-1} , and time (T) has dimensions of T\mathrm{T} . To express density ( ρ\rho ), which has dimensions of ML−3\mathrm{ML}^{-3} , in terms of F, V, and T, we need to find the exponents of F, V, and T.

Let the dimensions of density be expressed as:

[M]a[L]b[T]c\mathrm{[M]}^a \mathrm{[L]}^b \mathrm{[T]}^c

Substituting the dimensions of F, V, and T:

[F]a[V]b[T]c=(MLT−2)a(LT−1)b(T)c\mathrm{[F]}^a \mathrm{[V]}^b \mathrm{[T]}^c = (\mathrm{MLT}^{-2})^a (\mathrm{LT}^{-1})^b (\mathrm{T})^c

Since density has dimensions of ML−3\mathrm{ML}^{-3} , we can set up the following equations:

a=1a = 1 (for the mass term M)

a+b=−3a + b = -3 (for the length term L)

−2a−b+c=0-2a - b + c = 0 (for the time term T)

Solving these equations, we get:

a=1a = 1

b=−4b = -4

c=−2c = -2

Thus, the dimensional formula of density in terms of F, V, and T is:

FV−4T−2\mathrm{FV}^{-4} \mathrm{T}^{-2}

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