Question

100 balls each of mass $m$ 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. $\frac{100 m v}{t}$
• B. $200 m v t$
• C. $\frac{200 m v}{t}$
• D. $\frac{m v}{100 t}$

Answer 1

Answer: (C)

$\frac{200 m v}{t}$

Answer 2

Pi​=Nm∪i^Pf​=−Nmvi^
N is Number of balls strikes with wall
N=100
ΔP=Pf​−Pi​=−2Nmvi^
=−200Nmi^^
FTotal ​=ΔtΔP​=−t200mvt​
∣F∣=t200mv​