I need help with a physics energy two questions?

A 7.41 kg bowling ball moves at 2.56 m/s. How fast must a 2.21 g Ping-Pong ball move so that the two balls have the same kinetic

energy? Answer in units of m/s.

A spring with a force constant of 5.4 N/m has a relaxed length of 2.59 m. When a mass is attached to the end of the spring and allowed to come to rest, the vertical length of the spring is 3.67 m.

Calculate the elastic potential energy stored in the spring.

Answer in units of J.

Thank you so very much!

2 Answers

  • 10 years ago
    Favorite Answer

    bowling ball: Ek = ½mv² = ½•7.41kg•(2.56m/s)² = 24.3 J

    ping-pong: Ek = 24.3 J = ½•0.00221kg•v²

    v = 148 m/s ←

    Δx = 3.67m - 2.59m = 1.08 m

    Ep = ½kx² = ½•5.4N/m•(1.08m)² = 3.15 J ←

  • 10 years ago

    for 1



    Same energy = P1=P2


    Rearrange and solve for V

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