Suvat equations -- car braking hard to avoid a collision 1. The problem statement, all variables and given/known data A car (A) is speeding along a rural road, of width 4m with a speed of 25m/s when the driver sees another vehicle (B) of length 3.5m just starting to cross the road at a point 40m ahead. The drivers reaction time is 0.80s, and the maximum deceleration with the brakes fully applied is 5.5m/s/s, If the car can be assumed to decelerate uniformly without swerving etc., calculate: a) The distance travelled by the car during the drivers reaction time b) The car's (A) velocity when it reaches the position of the other vehicle (B) c) Total time which has elapsed from first sighting until car A reaches vehicle B d) The minimum constant velocity of vehicle B so that the car A does not collide with it 2. Relevant equations SUVAT Equations 3. The attempt at a solution a) s= u=25m/s v= a=-5.5m/s/s t=0.80 s=ut+0.5(at2) s=18.24m b) s=40m u=25m/s v= a=-5.5m/s/s t= v2=u2+2as v2=252+2(-5.5)(40) v=13.60m/s c) s=40m u=25m/s v=13.60m/s a=-5.5m/s/s t= v=u+at 13.60=25-5.5t t=(13.60-25)/-5.5=2.07s d) Rather unsure on this one: s= 3.5m u= v= a=0m/s/s t=2.07s I never calculated anything for d) because I am really unsure. Any help is appreciated!