The bus movingwith a speed `42km//h` is brought to a stop by brakes after `6m`. If the same bus is moving at a speed of `90km//h`, then the minimum stopping distance is

Options

A. `15.48m`
B. `18.64m`
C. `22.13m`
D. `27.55m`

Answer

D

Explanation

`u=42xx5/18=11.66m//s`
and `v=0`
So, `s_(1)=6m`
when `u=90xx5/18=25m//s`
and `v=0`
then `S_(2)=?`
Case I
`v^(2)=u^(2)+2as_(1)`
`=0(11.66)^(2)+2axx6(s_(1)=6m)`
`a=(-11.66xx11.66)/12`
`impliesa=-11.33m//s^(2)`
Case II
`v^(2)=u^(2)=2as_(2)`
`=0=(25)^(2)+2(-11.33)xxs_(2)`
`s_(2)=625/(2xx11.33)=27.5m`