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Thread: ned help on a conservation of energy problem please

  1. #1 ned help on a conservation of energy problem please 
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    A 4.0x10^4 kg roller coaster starts from rest at point A. Neglecting friction, calculate its potential energy relative to the ground, its kenetic energy, and its speed at points B, C, and D

    i found the potential energy of all points, i just need to know how to calculate the speed first, because i need speed to calculate kinetic energy

    we know that acceleration due to gravity is 9.81 m/s ^2

    point B is at the bottom of a slope which is 15m above the ground and the mass of the roller coaster is 4.0 x 10^4 kg heavy, how would i calculate the speed of the roller coaster at this point?

    any help would be greatly appreciated!


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  3. #2 Re: ned help on a conservation of energy problem please 
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    Quote Originally Posted by imppy725
    A 4.0x10^4 kg roller coaster starts from rest at point A. Neglecting friction, calculate its potential energy relative to the ground, its kenetic energy, and its speed at points B, C, and D

    i found the potential energy of all points, i just need to know how to calculate the speed first, because i need speed to calculate kinetic energy

    we know that acceleration due to gravity is 9.81 m/s ^2

    point B is at the bottom of a slope which is 15m above the ground and the mass of the roller coaster is 4.0 x 10^4 kg heavy, how would i calculate the speed of the roller coaster at this point?

    any help would be greatly appreciated!
    v<sup>2</sup> = 2*g*delta(h)

    i need speed to calculate kinetic energy
    No... KE(top) + PE(top) = KE(bottom) + PE(bottom)

    (Conservation of energy.)

    cheers


    "... the polhode rolls without slipping on the herpolhode lying in the invariable plane."
    ~Footnote in Goldstein's Mechanics, 3rd ed. p. 202
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