Question

Which of these physical quantities has base units kgm2s-2?

A. Pressure B. Energy C. Power D. Momentum

Intensity is defined as power per unit area, What is the units of intensity?

Answer 1

Pressure(P)=$\frac{F}{A}$

$F=[M^1L^1T^{-2}]\\A=[M^0L^2T^0]$

$P=\frac{[M^1L^1T^{-2}]}{[M^0L^2T^0]}=[M^1L^{-1}T^{-2}]$

Pressure=$N /m^2$

Energy (E)=(w)=$F\times dr$

$$W=[M^1L^1T^{-2}][L^1]=[M^1L^2T^{-2}]$$

Unit =$Kgm^2sec^{-2}$

Power=$\frac{E}{t}=\frac{[ML^2T^{-2}]}{[T]}=[ML^2T^{-3}]$

Unit=J/sec

Momentum (p) =mv

$P=[M][LT^{-1}]=[MLT^{-1}]$

Unit =kgm/sec

Option (b) is correct option

Intensity(I)=$\frac{P}{A}$

Power=J/sec

Area=m²

$I=\frac{J/sec}{m^2}=\frac{J}{m^2\times sec}$