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

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

1.	A car is moving with a velocity of 20m//s. The driver sees a stationary truck ahead at a distance of 100m. After some reaction time Deltat the brakes are applied producing a retardation of 4m//s^(2). What is the maximum reaction time to avoid collision?
Answer» Solution :After applying the breaks, LET S be the distanc covered by the car before COMING to rest. `V^(2)=u^(2)+2as` covers distance s `therefore 0=20^(2)-2xx4s therefore s=(400)/(8)=50m` The car covers 50 m 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 `Deltat` `therefore (50)/(Deltat)=20 therefore Deltat=(50)/(20)=2.5s` `therefore` The maximum reaction time `Deltat=2.5s`