Question

n small balls each of mass m impinge elastically each second
on a surface with velocity v. The force experienced by the
surface will be
(a) 1/2 mnv
(b) 2 mnv
(c) mnv (d) 2 mnv

Answer 1

Answer:

(d) 2 mnv

Explanation:

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Answer 2

Question:-

n small balls each of mass m impinge elastically each second

on a surface with velocity v. The force experienced by the

surface will be

(a) 1/2 mnv

(b) 2 mnv

(c) mnv (d) 2 mnv

${\red{\underline{\underline{\bold{Answer:-}}}}}$

(d) 2 mnv right answer

${\green{\underline{\underline{\bold{Explanation:-}}}}}$

Given :

mass of each ball =m kg

velocity= um/s

In elastic collision :

Change in momentum=mu−(−mu)

=mu+mu

=2mu

For N balls change in momentum:

Δp=N×2mu

Rate of change of momentum=Δp/t=N2mu/1sec

=N2mu

According to Netwon's Second Law

F=Δp/t

F=2Nmv

Hence,

option B is correct .