Question

when brakes are applied to a car is recorded uniformly at 5 M per second square and stopped after 15 seconds find the initial velocity of the car

Answer 1

a= -2 m/s²
t= 10 secs
According to 1st equation of motion,
v=u+at
So,
0=u+(-2*10)
or, u=2*10  =20 m/s

Answer: 20 m/s

Answer 2

Hey your required solution is here----
--
$we \: have \: \: a = - 5ms - ^{2} \: t = 15s \: v = 0 \\ now \: v = u + at \\ \: \: \: \: \: \: = > u = \frac{at}{v} \\ \: \: \: \: = = > u = \frac{ - 5 \times 15}{0} \\ \: \: \: = = > u = 75ms - ^{1} Ans.$
Hey your required solution is here----
Hope it helps you now!!!!!!