Q. $10,000$ small balls, each weighing $1\ gm$, strike one square $cm$ of area per second with a velocity $100\ m/s$ in a normal direction and rebound with the same velocity. The value of pressure on the surface will be
A) $2 \times 10^{3}\ N/m^{2}$
B) $2 \times 10^{5}\ N/m^{2}$
C) $10^{7}\ N/m^{2}$
D) $2 \times 10^{7}\ N/m^{2}$
Explanation
(d) $P = \frac{F}{A} = \frac{n\left\lbrack mv - ( - mv) \right\rbrack}{A} = \frac{2mnv}{A}$
$= \frac{2 \times 10^{- 3} \times 10^{4} \times 10^{2}}{10^{- 4}} = 2 \times 10^{7}\ N/m^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.