Potential Energy & Niagara Falls

In summary, to calculate the change in potential energy of 2.8kg of water as it passes over Niagara Falls, we use the equation U=mgh and plug in the values (2.8)(9.8)(50) to get 1372J. However, this is the potential energy at the top, and the problem is asking for the change in potential energy as the water falls from the top to the bottom. Therefore, we need to account for the decrease in height and the negative sign in the equation, resulting in a final change in potential energy of -1372J.
  • #1
warrior2014
34
0

Homework Statement


Calculate the change in potential energy of 2.8kg of water as it passes over Niagara falls (a distance of 50m)


Homework Equations


U= mgh


The Attempt at a Solution



I plugged in the values into the equation U=mgh= (2.8)(9.8)(50)=1372J but it was the wrong answer. I'm not exactly sure what I am doing wrong. Any help is appreciated!
 
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  • #2
You are calculating the PE at the top. What's the PE at the bottom? The problem is asking for the change in PE as the water falls from the top to the bottom.
 
  • #3
Would it be a negative number?
 
  • #4
if the height at the bottom is 0, then wouldn't the PE at the bottom also be 0? so then PE would be 1372J? I'm kind of confused.
 
  • #5
Does a body gain or lose PE as it falls to ground?
 
  • #6
lose?
 
  • #7
So, in falling it loses PE. Hence the negative sign.
 
  • #8
oh okay. thank you! now I understand.
 

FAQ: Potential Energy & Niagara Falls

What is potential energy?

Potential energy is the stored energy that an object possesses due to its position or configuration. It can be converted into other forms of energy, such as kinetic energy, when the object moves or changes its position.

How does potential energy relate to Niagara Falls?

Niagara Falls has potential energy due to its position at the top of a steep cliff. The water at the top has gravitational potential energy, which is converted into kinetic energy as the water falls down the cliff.

What factors affect the potential energy of Niagara Falls?

The potential energy of Niagara Falls is affected by the mass of the water, the height of the falls, and the acceleration due to gravity. Additionally, the width of the falls and the shape of the cliffs can also impact the potential energy.

Can potential energy be harnessed at Niagara Falls?

Yes, potential energy at Niagara Falls can be harnessed by using hydroelectric power. This involves capturing the kinetic energy of the falling water and converting it into electricity.

What are some real-world applications of potential energy at Niagara Falls?

Aside from hydroelectric power, potential energy at Niagara Falls is also used for recreational activities like bungee jumping and zip lining. Additionally, the potential energy of the falls has been used for transportation by powering the Niagara Gorge Railroad.

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