Q82 / 90 · JEE Main 2018 (08 Apr) · Physics

The mass of a hydrogen molecule is $3.32 \times 10^{- 27} kg .$ If $10^{23}$ hydrogen molecules strike, per second, a fixed wall of the area $2 {cm}^{2}$ at an angle of $45^{o}$ to the normal, and rebound elastically with a speed of $10^{3} m s^{- 1},$ then the pressure on the wall is nearly:

A
$4.70 \times 10^{2} N m^{- 2}$
Correct answer
B
$2.35 \times 10^{3} N m^{- 2}$
C
$4.70 \times 10^{3} N m^{- 2}$
D
$2.35 \times 10^{2} N m^{- 2}$

Solution

$F = 2 m n V c o s θ$ $\Rightarrow P = \frac{2 m n V c o s θ}{A}$

$\Rightarrow P = \frac{2 \times 3.32 \times 10^{- 27} \times 10^{23} \times 10^{3}}{\sqrt{2} \times 2 \times 10^{- 4}}$

$\Rightarrow P = 2.35 \times 10^{3} N m^{- 2}$

Hence, the correct answer is option: 'B'.

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The mass of a hydrogen molecule is 3.32×10-27 kg. If 1023 hydrogen molecules strike, per second, a fixed wall of the area 2 cm2 at an angle of 45o to the normal, and rebound elastically with a speed of 103 m s-1, then the pressure on the wall is nearly:

Solution

Relevant Questions

The mass of a hydrogen molecule is $3.32 \times 10^{- 27} kg .$ If $10^{23}$ hydrogen molecules strike, per second, a fixed wall of the area $2 {cm}^{2}$ at an angle of $45^{o}$ to the normal, and rebound elastically with a speed of $10^{3} m s^{- 1},$ then the pressure on the wall is nearly: