Question

Find the initial velocity of a car which is stopped in 10 s by applying breaks. Retardation due to brakes 2.5m/s .

Answer 1

final velocity=0 (came to rest)
acceleration=-2.5m/s(retardation)
time=10s
acceleration=final velocity-initial velocity/time
-2 .5=0-u/10
-25=-u

hope it helps

Answer 2

u=?
v=0(came to rest)
a=-2.5m/s
t=10s
v=u+at
0=u+-2.5×10
-u=-25
u=25m/s