IMPORTANT ANNOUNCEMENTS

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        ENERGY

All energy has been destroyed.
Oh, wait, there is a thermodynamic law that addresses this.

Some thoughts for Page 6: Energy, Work, Net Force, NonConservative Forces...

MOVIES

Please note: If the movie is too small,
please watch via youtube using the YOUTUBE button on bottom right of each video.
And, some videos have much higher quality. Find the HD version using the gear icon.
Energy: Part 1, Calculation Sensor 


Energy: Part 2, Using Workbooks 



Energy: Part 3, Using Graphs 



Energy: Part 4, Start—Stop Conditions 




There are a number of videos below for helping with analysis for Energy Lab.

We need to measure and calculate Sin(Theta.) 
We won't know this value absolutely; we will have uncertainty.
Watch this video in HD and full screen:






Total Energy needs the correct shape! 
This shape is controlled by the calculation of Sin(Theta.) 
What should total energy look like?
Watch this video in HD and full screen:





We need to shift the Potential Energy so that there is no potential energy 
at the beginning of the experiment. 
This allows us to also find where exactly the experimental motion ends 
(where Potential is zero again and where Total and Kinetic meet again.)
Watch this video in HD and full screen:







Begin Q&A Forum for "ENERGY"

How much energy is lost in an internal cubustion engine?Anonymous
Wed. 17, Oct 2007, 21:49
By "lost" do you mean gone, non-existent?
No energy is lost!
Is some (a lot) of the energy not transfered to the drive shaft? Yes!
:)
Douglas
Thu. 18, Oct 2007, 08:41

How can energy lost in the form of heat be recycled into a reusable form of energy for a system?Soler, Lynn
Wed. 17, Oct 2007, 22:27
lsoler002@msn.com
It depends on lots of factors. What is heating up, for instance.

I have a wood burning stove at home. It is really amazing to watch. When I get the two vents set just right, the wood sits on the bottom and the flames hoover about five inches above the wood! The flames are more like jets at that point. It is wild to see and hear!

My stove "recycles" the hot combustible gasses (and small floating fragments) via convection and redirects these gases over the wood where the air is hot. The gasses burn and recycle until it is cool enough to exhaust itself nearly emission free (2grams emission / hour.) When my stove is running most effeciently the "smoke" out of the stack is nearly clear (transparent!) In this setting one load of cheap, pine 2x4's can burn for up to 10+ hours!

This is just one example of attempting to re-capture energy and use as much as possible.

(P.S. I also put a large pot of water on the stove's top surface. It evaporate water and adds humidity to Denver's dry air in my house. Sometimes, I even bake some rolls!)
Douglas
Thu. 18, Oct 2007, 08:49

In workbook page 6, it asked for the "standard deviation". How do I find the standard deviation and what does it mean in energy?Anonymous
Fri. 26, Oct 2007, 23:36
The standard deviation is asked in regards to the angle, not the energy.
It might even be better to find simply sinθ and its standard deviation rather than θ.

If you create a table of values in a spreadsheet in cell A1 through A3, then you can find the average by entering this in cell A4
=Average(A1:A3)
And type this in cell A5 for the Standard Deviation:
=StDev(A1:A3)
Douglas
Sat. 27, Oct 2007, 06:11

The energy lab is a three week lab correct? Is the post lab really due for the lab this week before class or will that deadline be extended?
Anonymous
Tue. 30, Oct 2007, 16:28
Oops, my biff.
The deadline is now fixed for the week of November 5th plus one day. :)
Douglas
Wed. 31, Oct 2007, 08:34

Lots of students have asked about how to find a Potential Energy equation that Data Studio can use. Data Studio can only measure x. It can't measure h which is needed for U = mgh. Can I produce a huge hint?Howey, Douglas
Mon. 17, Mar 2008, 14:15
jmart353@msudenver.edu
Okay, here it is:
Douglas
Mon. 17, Mar 2008, 14:20

Lots of students have asked about how to measure sin(θ) for the incline. We need to know that value (sin(θ)) for the new U equation. Is there a humungous hint?Howey, Douglas
Mon. 17, Mar 2008, 14:16
jmart353@msudenver.edu
Use the Vernier plunger to measure the h's seen below.
Douglas
Mon. 17, Mar 2008, 14:21

I am a little confused on question 6 in the postlab. What do we do with acceleration? I can not think of an equation to use to figure out the height.Cooper, Ryan
Mon. 27, Oct 2008, 18:45
RlcAvs99@msn.com
Try to go back to the Data and Graphs lab. We created an incline there, found the acceleration and had a relationship between acceleration and height of riser block. Or, draw a free-body diagram to find the acceleration along the incline. (Sin(θ) is involved.)Douglas
Tue. 28, Oct 2008, 07:54

I am confused about question # 1 on the post lab quiz. When you say the 'levelness' do you mean what is the best way to determine when the slope of the glider track is zero? Can you please clarify the question for me?Anonymous
Tue. 28, Oct 2008, 12:17
Yes, is the track level? Is the slope of the track 0? How can you test for this condition?Douglas
Wed. 29, Oct 2008, 08:30

for question 2 in postlab. Does Kinetic enery go from max to zero as the car start from lowest and stop at its highest motionpham, chuong
Tue. 07, Jul 2009, 15:35
chuongpham@netzero.com
I can't answer that as that is a main point of the experiment. If KE is 1/2 m*v*v, then what if v is zero, what is KE? What is v at highest point reached by cart?Douglas
Tue. 07, Jul 2009, 16:08

In our lab, we were wondering if we should use the same coordinate system for the trip up and the trip down. We wanted to make the work of friction negative in both directions. Thank you.Anonymous
Thu. 28, Oct 2010, 03:41
Use the same coordinate system for both directions.Douglas
Thu. 28, Oct 2010, 04:05

Hello Douglas,
Question 6 of post-lab provides enough information to calculate total height; we are asked to calculate the height of the block. We are told that the block is placed under the leg. Considering that total height consists of the height of the block + the height of the leg, shouldn't we be given the height of the leg in order to be able to determine the height of the block? Thank you.
Anonymous
Sun. 31, Oct 2010, 12:02
Without the block the track is supposed to be level while sitting on the table. With the block, the only difference in height from one support leg to the next is the block. The support legs could be 2 cm or 2 m high and the block would still provide the same angle.Douglas
Mon. 01, Nov 2010, 03:13

Our potential energy does not start at zero. The equations have been checked. Any ideas on this? Anonymous
Sun. 15, Jul 2012, 22:34
See the third video at the energy webpage. It covers this in detail.Douglas
Mon. 16, Jul 2012, 04:45

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