NEET-XII-Physics
24: Kinetic Theory of Gases
- #16Find the average magnitude of linear momentum of a helium molecule in a sample of helium gas at 0°C. Mass of a helium molecule = 6.64 × 10-27 kg and Boltzmann constant = 1.38 × 10-23 J K-1.Ans : Here,
m = 6.64 × 10-27 kg
T = 273 K
`` \,\mathrm{\,Average\,}\,\mathrm{\,speed\,}\,\mathrm{\,of\,}\,\mathrm{\,the\,}\,\mathrm{\,He\,}\,\mathrm{\,atom\,}\,\mathrm{\,is\,}\,\mathrm{\,given\,}\,\mathrm{\,by\,}``
`` {\,\mathrm{\,V\,}}_{\,\mathrm{\,avg\,}}=\sqrt{\frac{8kT}{\pi m}}``
`` =\sqrt{\frac{8\times 1.38\times {10}^{-23}\times 273}{3.14\times 6.64\times {10}^{-27}}}``
`` =1202.31``
`` ``
We know,
Momentum = m × Vavg
= 6.64 × 10-27 × 1201.35
= 7.97 × 10-24
= 8 × 10-24 kg-m/s