8 A car accelerates at a rate of 10m/s for a time of 4s and it reaches a speed of 52m/s . calculate the initial value
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From the First Law of Motion

Vf = Vi + at

"It reaches a speed of 52m/s" meaning the Final speed Vf=52

a(acceleration)=10m/s²

t=4s

Applying the formula

52=Vi + 10(4)

Vi = 52-40

Vi = 12m/s

We shall use the formula
v = u + at
where
v = final velocity
u = intal velocity
t = time
a =  acceleration

For the given problem,
v = 11.4 m/s (final elocity)
u = 28.6 m/s (initial velocity)
a = -1.35 m/s^2  (negative acceleration for braking)

Therefore
11.4 = 28.6 - 1.35t
1.35t = 28.6 - 11.4 = 17.2
t = 17.2/1.35 = 12.7407 s

 12.74 s