A car is moving with a velocity of 20 m/s. The driver sees a stationary truck ahead at a distance of 100 m. After some reaction time Deltat the brakes are applied producing a retardation of 4 m//s^2? What is the maximum reaction time to avoid collision ?

A car is moving with a velocity of 20 m/s. The driver sees a stationar

1.	A car is moving with a velocity of 20 m/s. The driver sees a stationary truck ahead at a distance of 100 m. After some reaction time Deltat the brakes are applied producing a retardation of 4 m//s^2? What is the maximum reaction time to avoid collision ?
Answer» SOLUTION :After applyiing the breaks LET S be the distance covered by the car before coming to rest `v^(2)=U^(2)+2as` COVER distance s `0=20^(2)-2 xx 4s ""s=(400)/(8)=50m` The car covers 50m after applying breaks To AVOID the clash, the remaining distance 100-50=50m must be covered by the car with uniform velocity 20m/s during the reaction time `trianglet` `(50)/(trianglet)=20""trianglet=(50)/(20)=2.5s` The maximum reaction time `trianglet=2.5s`