Acceleration 5451

The driver of a car traveling at a given moment at a speed of 72 km/h decides to overtake a car traveling at the same speed. Therefore, during 4.0 seconds, increase the speed to 90 km/h. Calculate how big his acceleration was and what path he covered when the speed increased.

Correct answer:

a =  1.25 m/s
s =  90 m

Step-by-step explanation:

$$\begin{gathered} v_1=72/3.6=20\text{m/s} \\ {v}_2=90/3.6=25\text{m/s} \\ t=4\text{s} \\ a=(v_2-v_1)/t=(25-20)/4=1.25\text{m/s} \end{gathered}$$

$s=v_1\cdot t+\frac{1}{2}\cdot a\cdot t^2=20\cdot 4+\frac{1}{2}\cdot 1.25\cdot 4^2=90\text{m}$

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