JEE Advanced 2019 · Paper 1 · Physics Q11

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PhysicsMultiple correct+4 / -1Question 11 of 54

Let us consider a system of units in which mass and angular momentum are dimensionless. If length has dimension of $L$ , which of the following statement(s) is/are correct?

The dimension of linear momentum is

L^{-1}

The dimension of energy is

L^{-2}

The dimension of force is

L^{-3}

The dimension of power is

L^{-5}

Answer and worked solution

Official answer: A, B, C

Mass is dimensionless, and angular momentum $[ML^2T^{-1}]$ is dimensionless, so $[T]=L^2$ .

(A) Momentum $[MLT^{-1}]=L\cdot L^{-2}=L^{-1}$ . True.
(B) Energy $[ML^2T^{-2}]=L^2\cdot L^{-4}=L^{-2}$ . True.
(C) Force $[MLT^{-2}]=L\cdot L^{-4}=L^{-3}$ . True.
(D) Power is energy/time, $L^{-2}/L^2=L^{-4}$ , not $L^{-5}$ . False.

(A), (B), (C)

Topics:Dimensional analysis

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JEE Advanced 2019 · Paper 1, Physics question 11