physics

Niagara Falls are 50m high. Calculate the potential energy of 5kg of water at the top,relative to the bottom. What is the kinetic energy of this water just before it reaches the bottom, and what happens to the bottom, and what to the energy after the reaches the bottom?

  1. 👍 0
  2. 👎 0
  3. 👁 234
  1. energy at the top: mgh=5*9.8*50 joules
    energy at the bottom (ignoring energy loss on the way)=1/2 m v^2
    or KE=5*9.8*50
    this energy turns to heat, and warms the water.
    Lord Kelvin wanted to demonstrate this, he created a large thermometer, to measure the temperature of the water at the top, then run to the bottom and measure it there (Lucerne, Switzerland). To his amazement, the water at the bottom was COOLER, not warmer. This lead to his discovery that evaporation of the water on the way down took energy (evaporation is endothermic), so water at the bottom was always cooler.

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A certain mass of water at the top of Niagara Falls has a temperature of +10.0 degrees Celsius. It falls a distance of 50m. Assuming that all its potential energy is converted into thermal energy, calculate the temperature of the

    asked by Josée on December 14, 2015
  2. physics

    water flow over a falls 12.5m high. If the potential energy of the water is all converted to thermal energy calculate the temperature difference between the water at the top and buttom of the falls.

    asked by Nathan siafa on May 22, 2013
  3. physics

    Approximately 5.5 X10^6 kg of water fall 50m over Niagara Falls each second. a) What is the decrease in the gravitational potential energy of the water-Earth system each second? b) If all this energy could be converted to

    asked by Brian on January 10, 2007
  4. physics

    Approximately 5.5 X10^6 kg of water fall 50m over Niagara Falls each second. a) What is the decrease in the gravitational potential energy of the water-Earth system each second? b) If all this energy could be converted to

    asked by Brian on January 11, 2007
  5. principles of physics

    Calculate the change in potential energy of 7.8 million kg of water dropping 50 m over Niagara Falls.

    asked by britches on February 22, 2012
  6. Physics

    Water flows over a section of Niagara Falls at a rate of 1.2×106 kg/ s and falls 50m. How many 60W bulbs can be lit with this power?

    asked by Anonymous on June 30, 2011
  7. math

    The upper Angel Falls, the highest waterfall on Earth, is 750m higher than Niagara Falls. If each of the falls were 7m lower, the upper Angel Falls would be 16 times as high as Niagara Falls. How high is each waterfall? Use a

    asked by jessica on August 19, 2009
  8. 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.

    asked by Benny f on April 3, 2016
  9. PHYSICS

    A box slides down a frictionless, 10-meter, 30o incline. Calculate the gravitational potential energy at both the beginning and end of the motion. Calculate the work done by GRAVITY as the box slides down the incline. Compare this

    asked by Help! on March 23, 2016
  10. Physics

    please can u check my answer Here are the questions: 1. A 0.45 kg book is resting on a dessktop 0.64 m high. Calculate the book's potential energy relative to a)the desktop? b)the floor. 2. A 0.636 kg basketball has a potential

    asked by Anonymous on April 9, 2011

More Similar Questions