Units & Dimensions

JEE Main level, single correct, medium

128 of 149

Question 128 of 149

Time (T)\left(T\right), velocity (C)\left(C\right) and angular momentum (h)\left(h\right) are chosen as fundamental quantities instead of mass, length and time. In terms of these, the dimensions of mass would be:

Show answer and solution

Answer: (A) [M]=[T−1C−2h]\left[M\right]=\left[{T}^{-1}{C}^{-2}h\right]

M∝TxCyhzM\propto {T}^{x}{C}^{y}{h}^{z}
M1L0T0=(T1)x(L1T−1)y(M1L2T−1)z{M}^{1}{L}^{0}{T}^{0}={\left({T}^{1}\right)}^{x}{\left({L}^{1}{T}^{-1}\right)}^{y}{\left({M}^{1}{L}^{2}{T}^{-1}\right)}^{z}
[M1L0T0]=[MzLy+2zTx−y−z][{M}^{1}{L}^{0}{T}^{0}]=[{M}^{z}{L}^{y+2z}{T}^{x-y-z}]]
⟹z=1⟹z=1
y+2z=0,x−y−z=0y+2z=0,x-y-z=0
solvingsolving
y=−2y=-2
and
x=−1x=-1
M⇒[T−1C−2h1]M\Rightarrow \left[{T}^{-1}{C}^{-2}{h}^{1}\right]

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Units & Dimensions (Dimensions), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.