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Math Help - Stuck on three physics tasks (momentum, force)

  1. #1
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    Stuck on three physics tasks (momentum, force)

    Could you please help me with these three tasks?

    1. A trolley weighing 16 000kg is moving along a horizontal surface with a velocity od 6m/s. What braking force would cause it to brake on a distance of 10m and how long it would take?
    2. A cycler is going through the winding, cycling on a circle of radius 6m and is slanting with alpha=75^ to the horizontal surface. What's his velocity?
    3. A body of small dimensions is sliding from an apex of a sphere of radius R down. At what height h from the apex the body will lose contact from the sphere? (assume the friction is low)

    My thoghts:

    1. a = F/m = ΔV/t. So ΔV = 6m/s, m=16 000kg, s = 10m and F = mΔV/Δt. We know neither F nor t so how could I solve this? It's just one equation but two unknown variables.
    2. We have two forces on the cycler - centrifugal force and friction. They are equal (or at least should be? Though I don't know why...) so we have T=Fc and thus \frac{mv^{2}}{R}=\mu F_{N}. How should I use it, though, if I have only 75^ and the radius given?
    3. Oh my, been cracking my head over it for some time and know not even where to start...

    Could you please hlp me understand?
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  2. #2
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    Re: Stuck on three physics tasks (momentum, force)

    1.

    m = 16,000kg
    v = 6m/s
    S = 10m

    The velocity equation is v = at+v_0
    The distance equation is S = \frac{1}{2}at^2+v_0 t

    Try and use those two equations along with the information you've been given to solve for both a and t
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