At 300 K, what is the rms speed of Helium atom? [mass of He atom is 4u, 1u = 1.66 × 10⁻²⁷ kg; kB = 1.38 × 10⁻²

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Q. At 300 K, what is the rms speed of Helium atom? [mass of He atom is 4u, 1u = 1.66 \times 10⁻²⁷ kg; k_B = 1.38 \times 10⁻²³ J/K]

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½m v̄² = (3/2)k_BT gives v̄² = 3k_BT/m; with m = 4 × 1.66×10⁻²⁷ kg this is 187.05 × 10⁴ m²/s², so v_rms ≈ 1368 m/s.

Given T = 300 K and m = 4 × 1.66 × 10⁻²⁷ kg. The equipartition result for the average translational kinetic energy is

$\overline{KE} = \tfrac{1}{2}m\overline{v^2} = \tfrac{3}{2}k_B T$ …

Q.At 300 K, what is the rms speed of Helium atom? [mass of He atom is 4u, 1u = 1.66 × 10⁻²⁷ kg; k_B = 1.38 × 10⁻²³ J/K]