Could someone please tell me what step I missed up on? I posted the steps to wha

Question

Could someone please tell me what step I missed up on? I posted the steps to what I did, but the answer is incorrect.

Two cars both cover a straight distance, d = 305 m, in time t = 85s. Car A moves at a constant velocity (vA). Car B moves at a constant acceleration (aB), starting from an initial velocity of viB = 8m/s. Assume both cars moving in the positive x-direction.

So, d = 305 m

t = 85s

viB = 8m/s

What is the final velocity of Car B?

—> x = 1/2 a t^2 + vi

305 = 1/2 a (85s)^2 + 8m/s

610 = a (7225) + 8

a = 0.08433 m/s

What is the acceleration of Car B?

—> vf = a t + vi

V = (0.08433m/s)(85) + 8 +==>15.168 m/s

Explanation / Answer

—> x = 1/2 a t^2 + vi*t

305 = 0.5*a (85)^2 + 8*85

305 = 8*85 + 0.5*85^2*a

aB = [305-8*85]/[0.5*85^2]

= - 0.1038 m/s^2

vB= u +at = 8-0.1038*85

= -0.823 m/s

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