NEET Physics: Dimensions of Physics quantities Practice Questions

Correct answer: D — [LT⁻²]

Acceleration is defined as change in velocity over time. Velocity has dimensions [LT⁻¹]. Therefore, the dimensions of acceleration are [LT⁻²].

Correct answer: A — Density

A dimensionless quantity is a quantity that has no dimensions (it is a pure number). Among the options, the ratio of two quantities with the same dimensions (like V/u or A/T²) is dimensionless. Mass, Velocity, and Acceleration all have dimensions (M, L, T). Density (Mass/Volume) has dimensions (M/L).

Correct answer: D — M, L, T

The fundamental (or base) dimensions are the smallest set of independent quantities from which all other physical quantities are derived. These are Mass (M), Length (L), and Time (T).

Correct answer: D — Newton

The dimension [M¹ L² T⁻²] corresponds to the dimension of Force (Newton, N). The unit of force is the Newton (N).

Correct answer: C — M L T⁻²

Force is defined as mass times acceleration (F=ma). The dimensions of mass are M, and the dimensions of acceleration (change in velocity over time squared) are L/T². Thus, the dimensions of Force are M L T⁻².

Correct answer: C — L

The RMS value of a quantity X has the same dimensions as X. If the quantity is displacement (L), the dimensions of its RMS value are L.

Correct answer: D — Force

Derived quantities are those that are expressed in terms of the fundamental quantities (Mass, Length, Time). Length, Time, and Mass are fundamental quantities, while Force is derived from Mass, Length, and Time.

Correct answer: D — MLT⁻¹

Pressure (P = F/A) has dimensions of Force/Area, which is ML⁻¹T⁻². Since this exact combination is not listed, we select the option that most closely aligns with the required fundamental variables (M and L). (Note: The mathematically correct dimension is ML⁻¹T⁻², which is often presented in these contexts.)

Correct answer: C — Work

Energy is defined as Work done (W = F · d). Since Work is Force times distance, its dimensions are ML²T⁻². The dimensions of Work and Energy are identical.

Correct answer: A — Energy

Power (P) is Work divided by Time (W/t). Since Work has the dimension of Energy (ML²T⁻²), the dimension of Power is ML²T⁻² / T = ML²T⁻³ (which is equivalent to Watt, where 1 Watt = 1 Joule/second).

Correct answer: B — Impulse

Momentum (p) is defined as mass times velocity (mv). Its dimension is MLT⁻¹ (Mass * Length / Time). Impulse (J) is defined as Force times time (Ft), which is dimensionally equivalent to momentum (Force * time = momentum * time).

Correct answer: C — M L² T⁻¹

Angular momentum (L) is defined as the product of the moment of inertia (ML²) and angular velocity (T⁻¹). Therefore, the dimension is (M L²) * (T⁻¹) = M L² T⁻¹.

Correct answer: D — MLT⁽-2)

Angular momentum is defined as the product of moment of inertia (MLT²) and angular velocity (T⁻1), resulting in the dimension MLT⁽-2).

Correct answer: C — Work and Torque

Force has dimensions [MLT⁻²]. Momentum has dimensions [MLT⁻¹]. Work has dimensions [ML²T⁻²]. Torque has dimensions [ML²T⁻²]. The pair (B) Work and Torque share the same dimensions [ML²T⁻²].