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Kinetic Theory

Question
CBSEENPH11020505

The mass of a hydrogen molecule is 3.32 x 10-27 kg. If 1023 hydrogen molecules strike, per second, a fixed wall of area 2cm2 at an angle of 45° to the normal, and rebound elastically with a speed of 103 m/s, then the pressure on the wall is nearly:

  • 4.70 x 102 N/m2

  • 2.35 x 103 N /m2

  • 4.70 x 103 N/m2

  • 2.35 x 102 N /m2

Solution

B.

2.35 x 103 N /m2

Change in momentum

P = P2J^  + P2J^ + P2i^ -P2i^P =  2P2J^  = IH molecule Iwalll = - 2P2J^  Pressure, P=FA = 2PAn (n = no. of particles)2 x 3.32 x 10-27x 103 x 10232 x 10-4= 2.35 x 103 N/m2