Laws Of Motion Question 264
Question: n small balls each of mass m impinge elastically each second on a surface with velocity u. The force experienced by the surface will be [MP PMT/PET 1998; RPET 2001; BHU 2001; MP PMT 2003]
Options:
A) mnu
B) 2 mnu
C) 4 mnu
D) $ \frac{1}{2}mnu $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \vec{F}=\frac{d\vec{p}}{dt}= $
Rate of change of momentum As balls collide elastically hence, rate of change of momentum of ball = $ n[mu-(mu)] $ = $ 2mnu $ i.e. $ F=2mnu $
