A motor car of mass 800kg traveling at 20m/s brought to rest by break over 100m calculate the average breaking force required
s = vt - 1/2 at^2
20t - 1/2 at^2 = 100
Also,
v = Vo-at, so
20-at = 0
at = 20
so,
20t - 1/2(20)t = 100
t=10
So, a = 2
F = ma = 800*2 = 1600N