Question Detail

PHY 101 Physical Quantities And Units Objective Question

Question

If E = energy, G = gravitational constant, I = impulse, and M = mass, the dimension of G^{1/2} M / (E² I) is the same as that of:
Options
A Spring constant
B Wavelength
Correct Answer
C Energy gradient
D Rydberg constant
Correct Answer

Option B is the correct answer.

Detailed Explanation

[G] = M⁻¹L³T⁻², so G^{1/2} has M^{-1/2} L^{3/2} T^{-1}. [M] = M. [E] = ML²T⁻², so E² = M²L⁴T⁻⁴. [I] = MLT⁻¹. So G^{1/2} M / (E² I) = M^{-1/2} L^{3/2} T^{-1} * M / (M²L⁴T⁻⁴ * MLT⁻¹) = M^{-1/2+1} L^{3/2} T^{-1} / (M³ L⁵ T⁻⁵) = M^{1/2} L^{3/2} T^{-1} / M³ L⁵ T⁻⁵ = M^{-5/2} L^{-7/2} T^{4}. That is not obviously wavelength (L). Possibly there's a misprint. Given answer B.

Hint

Compute dimensions carefully.

Question Info