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anonymous

  • one year ago

A car moving with a speed of 108 km/h is brought to rest in a distance of 60 m. The car's acceleration is -7.5 m/s/s. How much time did the car take to stop?

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  1. Michele_Laino
    • one year ago
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    the stopping work is given by the kinetic energy of the car, so if I call with \(F\) the stopping force, and with \(d\) the space traveled by the car, then we can write: \[Fd = \frac{1}{2}m{v^2}\] now, we have that \(F=ma\) where \(a\) is the deceleration, so we can write: \[mad = \frac{1}{2}m{v^2}\] and finally: \[d = \frac{{{v^2}}}{{2a}}\]

  2. Michele_Laino
    • one year ago
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    the requested time is given by the subsequent condition: \[0 = v - at\] please solve that equation for time \(t\). Of course \(v=108\;Km/h\)

  3. anonymous
    • one year ago
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    @Michele_Laino

  4. anonymous
    • one year ago
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    Thank you!!!!!!!!

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