posted by Sarah on .
I really don't get why I am getting this question wrong? Please can you explain to me how to do this question step by step so that I can understand it please? :( i have been stuck on this question for quite a while now.
Determine the stopping distances for an automobile with an initial speed of 89 km/h and human reaction time of 2.0 s for the following:
(a) an acceleration a = -4.0 m/s2.
(b) a = -8.0 m/s2.
v=89 km/h=89000/3600= 24.7 m/s.
The distance covered during the reaction time is
The distance covered during braking s₂
s₂=v₀²/2a =24.7²/2•4=76.3 m
s=s₁+s₂ =49.4+76.3 =125.7 m