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Energy Transfers occur continually in natural systems. For today's lesson, you will investigate the transfer of energy in waterfalls.
TME = KE + PE The total mechanical energy of a system is a sum of the kinetic and potential energies in that system. |
For this analysis, you will find the gravitational potential energy of 1 kilogram of water when it is at the top of the waterfall. As the water falls, its gravitational potential energy will change to kinetic energy as it falls faster. When it reaches the base of the falls, all of the gravitational potential energy at the start will transfer to kinetic energy at the bottom. By setting the starting gravitational potential energy equal to the kinetic energy at the base of the falls, you can solve for water's velocity at the bottom.
Waterfall
Do an internet search for waterfalls. You may select any waterfall IF you can find the following information about it:
1. a photo
2. the height of the water fall (be sure to include units . . . Is the height given to you in feet? in meters?)
3. Open PPT to create a one slide graphic that includes the photo and your energy analysis (See section below titled Analysis for instruction about what to put on your PPT slide). When you finish the slide, take a screen shot (Shift, Command, 4).
4. Take a screen shot of your PPT (Scroll down to see student example below)
5. Click on the on the padlet link below for your class.
1. a photo
2. the height of the water fall (be sure to include units . . . Is the height given to you in feet? in meters?)
3. Open PPT to create a one slide graphic that includes the photo and your energy analysis (See section below titled Analysis for instruction about what to put on your PPT slide). When you finish the slide, take a screen shot (Shift, Command, 4).
4. Take a screen shot of your PPT (Scroll down to see student example below)
5. Click on the on the padlet link below for your class.
6. In the lower right corner, click the +.
7. In upload arrow in the Padlet posting.
8. Choose the "PICK FILE" option that appears on the right of the screen. Search for your Screen shot and select it to post the image. DO NOT POST YOUR POWERPOINT FILE - POST THE SCREENSHOT IMAGE.
Analysis:
1. For one kilogram of water, find the velocity at the bottom of the waterfall.
According to the Law of Conservation of Energy, the total energy will be the same whether the water is at the top or bottom of the falls. Therefore, the Gravitational Potential Energy (Eg) of one kilogram of water at the top of the falls will transfer to Kinetic Energy (Ek) at the bottom of the falls. Since you can use Eg = mgh to find the Gravitional Potential Energy at the top, you can set that equal to the Kinetic Energy at the bottom and solve for velocity. Recall that EK = 1/2 m v v
1. For one kilogram of water, find the velocity at the bottom of the waterfall.
According to the Law of Conservation of Energy, the total energy will be the same whether the water is at the top or bottom of the falls. Therefore, the Gravitational Potential Energy (Eg) of one kilogram of water at the top of the falls will transfer to Kinetic Energy (Ek) at the bottom of the falls. Since you can use Eg = mgh to find the Gravitional Potential Energy at the top, you can set that equal to the Kinetic Energy at the bottom and solve for velocity. Recall that EK = 1/2 m v v
SHARE YOUR WORK
To turn in your work, you will post a screen shot of the PPT slide that you made on the padlet below.
See instructions (number 3 to 8 above) to create the image that you need to post. Click on the link to access the padlet.
See instructions (number 3 to 8 above) to create the image that you need to post. Click on the link to access the padlet.
A few years ago, Physics students had a similar assignment. Take a look at their work if you want to, but keep in mind that your assignment is a little different.