Friction/acceleration question

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    • Thread Starter

    The driver of a car travelling in a straight line, level road suddenly brakes.
    The car slides 10m in 2 seconds before stopping. Assuming constant deceleration, find the co-efficient of friction between the tyres and the road.

    I got given this question as homework after doing a lecture on turning moments so that put me on the wrong foot straight away.

    So ive assumed I need to find the velocity first using d/t the find the acceleration using s=u.t + 0.5.a.t2

    but then im lost. Can anyone point where im going wrong?

    You need to use F_f=\mu F_n

    The normal reaction F_n = mg, and the frictional force F_f=ma

    So you just need to calculate the acceleration of the car, and then you can find \mu
    • Thread Starter

    so do I need the mass value to complete this?

    No, the mass cancels out
    • Thread Starter

    would you also use this method for this question

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    or would this be better solved using the energy method?
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