A driver in a car traveling at a speed of 21.8 m/s sees a car 101 m away on the road. How long will it take for the car to uniformly decelerate to a complete stop in exactly 99 m?

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A driver in a car traveling at a speed of 21.8 m/s sees a car 101 m away on the road. How long will it take for the car to uniformly decelerate to a complete stop in exactly 99 m?

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Answer 1 · 2018-04-05T02:20:52

$9.1 s$ $9.1s$

Explanation:

Since we know that velocity is uniformly decelerating, we can take the average velocity:

$\frac{V_{i} + V_{f}}{2}$ $(V_i + V_f)/2$

Letting $V_{f}$ $V_f$ equal 0 m/s, we get $\frac{1}{2} \cdot 21.8 m$ $1/2*21.8m$ / $s$ $s$ or $10.9 m$ $10.9m$ / $s$ $s$ .

Now we know $V = \frac{d}{t}$ $V = d/t$ and rearranging this gives $t = \frac{d}{V}$ $t = d/V$ .

Substitute our velocity of 10.9m/s for V and 99m for d:
$t = \frac{99 m}{10.9 m \cdot s^{- 1}}$ $t=(99m)/(10.9m*s^-1)$ (Sorry for the $s^{- 1}$ $s^-1$ but otherwise I couldn't write m/s)

Finally we get $t = 9.1 s$ $t=9.1s$ (with significant figure rounding).

Hope this helps!

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A driver in a car traveling at a speed of 21.8 m/s sees a car 101 m away on the road. How long will it take for the car to uniformly decelerate to a complete stop in exactly 99 m?

1 Answer

Explanation:

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