A collar `B` of mass `2kg` is constrained to move along horizontal smooth and having spring constant `200Nm^(-1)` is underformed when the collar is it `A` If the collar starts from rest at `B` the normal reaction exerted by the track on the collar when it passes through `A` is

Options

A. `360N`
B. `720N`
C. `1440N`
D. `2880N`

Answer

C

Explanation

`E_(A)=E_(B)`
:. `(1)/(2)mv_(A)^(2)=(1)/(2)xx200xx(13-7)^(2)(m=2Kg)`
:. `v_(A)=60m//s`
At `A` , `N=(mv_(A)^(2))/(R)=((2)(60)^(2))/(S)=1440N`