Ask Question
13 December, 06:35

Using energy considerations and assuming negligible air resistance, show that a rock thrown from a bridge 20.0 m above water with an initial speed of 15.0 m/s strikes the water with a speed of 24.8 m/s independent of the direction thrown. (Hint: show that $$K_i + U_i = K_f + U_f) $$

+4
Answers (1)
  1. 13 December, 07:58
    0
    Given that,

    Height of the bridge is 20m

    Initial before he throws the rock

    The height is hi = 20 m

    Then, final height hitting the water

    hf = 0 m

    Initial speed the rock is throw

    Vi = 15m/s

    The final speed at which the rock hits the water

    Vf = 24.8 m/s

    Using conservation of energy given by the question hint

    Ki + Ui = Kf + Uf

    Where

    Ki is initial kinetic energy

    Ui is initial potential energy

    Kf is final kinetic energy

    Uf is final potential energy

    Then,

    Ki + Ui = Kf + Uf

    Where

    Ei = Ki + Ui

    Where Ei is initial energy

    Ei = ½mVi² + m•g•hi

    Ei = ½m * 15² + m * 9.8 * 20

    Ei = 112.5m + 196m

    Ei = 308.5m J

    Now,

    Ef = Kf + Uf

    Ef = ½mVf² + m•g•hf

    Ef = ½m * 24.8² + m * 9.8 * 0

    Ef = 307.52m + 0

    Ef = 307.52m J

    Since Ef ≈ Ei, then the rock thrown from the tip of a bridge is independent of the direction of throw
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “Using energy considerations and assuming negligible air resistance, show that a rock thrown from a bridge 20.0 m above water with an ...” in 📘 Physics if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers