The height of a certain waterfall is 33.2 m. When the water reaches the
bottom of the falls, its speed is 25.8 m/s. Neglecting air resistance, what is
the speed of the water at the top of the falls?

  1. 👍
  2. 👎
  3. 👁
  1. The speed is horizontal at the top, call it u
    it remains u all the way down because there is no horizontal force (acceleration).

    So we have a vertical problem first.

    v = g t
    h = (1/2) g t^2
    33.2 = 4.9 t^2
    t^2 = 6.77
    t = 2.60 seconds

    so v = 9.81 * 2.6 = 25.5 m/s down

    speed = s = 25.8 = sqrt(u^2 + 25.5^2)
    u^2 + 652 = 666
    u^2 = 13.64
    u = 3.69 m/s

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Science (Please check my answers)

    1) Which statement correctly identifies the relative levels of kinetic and potential energy in a hydroelectric dam?(1 point) Kinetic and potential energy are both highest at the top. Kinetic energy is highest at the top; potential

  2. Physics

    Salmon often jump waterfalls to reach their breeding grounds. Starting 2.00 m from a waterfall 0.55 m in height, at what minimum speed must a salmon jumping at an angle of 32.0 degrees leave the water to continue up stream? help


    The highest recorded waterfall in the world is found at Angel Falls in Venezuela. Its longest single waterfall has a height of 807 m. If water at the top of the falls is at 16.7°C, what is the maximum temperature of the water at

  4. calculus

    A water-trough is 10m long and has a cross-section which is the shape of an isosceles trapezoid that is 30cm wide at the bottom, 80cm wide at the top, and has height 50cm. If the trough is being fi lled with water at the rate of

  1. Physics

    A cylindrical container 1.5m tall contains mercury to a certain depth, d. The rest of the cylinder is filled with water. If the pressure at the bottom of the cylinder is two atmospheres, what is the depth d? I used this equation:

  2. Physics

    A uniform soda can of mass 0.135 kg is 12.4 cm tall and filled with 1.25 kg of soda (figure below). Then small holes are drilled in the top and bottom (with negligible loss of metal) to drain the soda. (Initially the soda can is

  3. physics

    A solid uniform marble and a block of ice, each with the same mass, start from rest at the same height above the bottom of a hill and move down it. The marble rolls without slipping, but the ice slides without friction. Find the

  4. Physics

    a solid ball and a cylinder roll down an inclined plane. which reaches the bottom first? A. The ball reaches the bottom first. B. The cylinder reaches the bottom first C. They arrive at the bottom at the same time D. It depends on

  1. Science

    which of the following statements best describes the energy of a waterfall? A) The water has Kinetic energy because of its position at the top of the water fall B)potential Energy changes to Kinetic Energy as the waterfalls.

  2. physics b

    In a waterfall, much of the energy of the falling water is converted into heat. If all the mechanical energy is converted into heat that stays in the water, how much of a rise in temperature occurs in a 100 m waterfall? For water,

  3. physics

    Salmon often jump waterfalls to reach their breeding grounds. Starting downstream, 2.95 m away from a waterfall 0.54 m in height, at what minimum speed must a salmon jumping at an angle of 29.7 ◦ leave the water to continue

  4. math

    A ball is thrown into the air with an upward velocity of 20 ft/s. Its height (h) in feet after t seconds is given by the function h(t) = –16t^2 + 20t + 2. How long does it take the ball to reach its maximum height? What is the

You can view more similar questions or ask a new question.