A car travelling at a speed of 30 km/hour is brought to a halt in 8 m by applying brakes. If the same car is travelling at 60 km/hour, it can be brought to a halt with the same braking force in

Options

A. 8 m
B. 16 m
C. 24 m
D. 32 m

Answer

D

Explanation

`v^(2)-u^(2)=2aS`
`:.a=(v^(2)-u^(2))/(2S)`
`=((0)^(2)-(25/3)^(2))/(2xx8)`
`=-(25/3)^(2)xx1/16`
For `u=60Kmh^(-1)`
`=50/3ms^(-1)`
`S=((0)^(2)-(50/3)^(2))/(2xxa)`
`=(-[50/3]^(-2))/(2xx[-(25/3)^(2)xx1/16])=32m`