A car is traveling at 100 km/h when the driver sees an accident 80 m ahead and slams on the brakes

Question

A car is traveling at 100 km/h when the driver sees an accident 80 m ahead and slams on the brakes. What constant deceleration is required to stop the car in time to avoid a pileup

Answer 1

100km/h = 100·1000m/s600s = 27.73 m/s

0² - 27.73² = 2a·80; a = - 27.73²/160 = - 4.81 m/s²