A car trvelling at `108 km h^(-1)` has its speed reduced to `36 km h^(-1)` after traelling a distance of `2000 m` Find the retardation (assumed uniform) and time taken for this process.

Explanation

`u=108 km h^(-1) =30 ms^(-1), v=36 km h^(-1) =10 m s^(-1)`
`v^(2)=u^(2)+2as`
`rArr 10^(2) =30^(2)+ 2axx200 rArr a=-2 m s^(-2)`
`v=u+at rArr 10=30-2t rArr t=10 s`.