A car slows to a stop in 5 seconds. if it was going 80 km/hr find the acceleration.

Given

time (t) = 5 seconds

Initial speed (u) = 80 km/hr = 22.2222m/s

final speed (v) = 0 km/hr = 0m/s

Note I change to m/s so as to be consistent with units

formula: V=U+at where a is acceleration

0=22.2222+5a

a=22.2222/5

acceleration = 4.44444 m/s^2