Question

3. A man applies the brakes and brings his car to rest in 1.5 s. If the retardation of the
brakes is 5 m/s", find the initial velocity of the car.​

Answer 1

initial velocity = u

final velocity = v

time = 1.5 s

retardation = a = -5 m/s

From first equ. of motion,

$v = u + at$

as given car comes to rest..so, final velocity becomes zero...,

$0 = u + 5 \times( - 1.5)$

$u = 5 \times 1.5$

$u = 7.5 \: m {s}^{ - 1}$

so..,

the velocity of car is 7.5 m/s