- Home
- Standard 11
- Physics
4-1.Newton's Laws of Motion
medium
$100$ balls each of mass moving with speed $v$ simultaneously strike a wall normally and reflected back with same speed, in time $t s$. The total force exerted by the balls on the wall is
A
$\frac{100 \,mv }{ t }$
B
$\frac{200\, mv }{ t }$
C
$200\,mvt$
D
$\frac{ mv }{100 t }$
(JEE MAIN-2023)
Solution
$P _{ i }= Nm v \hat{ i } \quad \overrightarrow{ P }_{ f }=- Nm v \hat{ i }$
$N$ is Number of balls strikes with wall
$N =100$
$\Delta \overrightarrow{ P } =\overrightarrow{ P }_{ f }-\overrightarrow{ P }_{ i }=-2 Nmv \hat{ i }$
$=-200\,Nm v \hat{ i }$
$\overrightarrow{ F }_{\text {Total }} =\frac{\Delta \overrightarrow{ P }}{\Delta t }=-\frac{200 mvt }{ t }$
$|\overrightarrow{ F }| =\frac{200\,mv }{ t }$
Standard 11
Physics
