Three particles have speeds 3, 4 and 12 cm s⁻¹ respectively. Their r.m.s. speed is ______ cm s⁻¹.
Physics · Mixed Chapter
JEE Main Practice

Question

Three particles have speeds 3, 4 and 12 cm s⁻¹ respectively. Their r.m.s. speed is ______ cm s⁻¹.

G1 Physics · Accepted Answer

Step 1: Root-mean-square speed is vᵣₘₛ = √[(v₁² + v₂² + v₃²)/3]. Step 2: vᵣₘₛ = √[(3² + 4² + 12²)/3] = √[(9 + 16 + 144)/3]. Step 3: vᵣₘₛ = √(169/3) = 13/√3 ≈ 7.50555 cm s⁻¹. Final answer: ≈ 7.505 cm s⁻¹ (PDF key truncates to three decimals).