Nabs asked in Science & MathematicsPhysics · 4 months ago

Physics Problem!!?

The question deals with two stage motion:

You are driving at 80km/h when you notice a person step out into the road. You need 0.43s to react and start braking. After that, you brake with an acceleration of -4.2m/s². Determine you total stopping distance.

I attempted this question and got a totally unrealistic answer :( Please help !!

1 Answer

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  • 4 months ago
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    80km/h = 80,000m/3600s = 200/9 m/s

    200/9 * 0.43  = 86/9 m before braking.

    After braking

    Vf² - Vo² = 2*a*d = 0² - (200/9)² = 2*(-4.2)*d = 

    -(200/9)²/(-2*4.2) = d = 58.8m

    Total distance = 68m with just 2 s.d.

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