# Answer to Question #15007 in Mechanics | Relativity for Erin

Question #15007

A car is traveling with a constant speed when the driver suddenly applies the brakes, giving the car a deceleration of 3.50 m/s2. If the car comes to a stop in a distance of 30.0 m, what was the car's original speed?

Expert's answer

Let's find the time elapsed to stop the car:

D = aT²/2 ==> T = √(2D/a) = √(2*30[m]/3.5[m/s²]) ≈ 14.49 [s].

So, the car's original speed was

V = aT ≈ 3.5[m/s²]*14.49[s] ≈ 50.72 [m/s].

D = aT²/2 ==> T = √(2D/a) = √(2*30[m]/3.5[m/s²]) ≈ 14.49 [s].

So, the car's original speed was

V = aT ≈ 3.5[m/s²]*14.49[s] ≈ 50.72 [m/s].

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