An oxygen molecule of mass 5.32 x 10^-26 kg, moving at 6.0 x 10^4 m/s strikes a wall at 90 degrees and rebounds without loss of speed. If the duration of the impact is 10^-9 seconds, calculate..?

Question

(a) the change in momentum of the molecule
(b) the force exerted by the wall on the molecule
(c) the force exerted by the molecule on the wall

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Answer 1 · 2016-10-23T12:52:10

Given

$m->"Mass of the molecule"=5.32xx19^"-26"kg$

$u->"Velocity of the molecule before"$
$" bombardment"=-6.0xx10^4m/s$

$v->"Velocity of the molecule after"$
$" bombardment"=+6.0xx10^4m/s$

$t->"Duration of impact"=10^-9s$

(a) So the change in momentum
$mv-"mu"=2xx5.32xx10^"-26"xx6xx10^4$

$=63.84xx10^"-22"" kgm/s"$

(b) The force exerted by the wall on the molecule is
$="change in momentum"/"time"$

$=(63.84xx10^"-22"" kgm/s")/(10^-9s)$
$=63.84xx10^-13N$

(c) The molecule will exerts same amount of reactionary force on the wall in oppsite direction.

So this force will be $=-63.84xx10^-13N$