WHAT TO DO WHEN MISSING A LAB

If you miss a lab, you will be allowed to take the make-up lab, on two conditions:
- you must miss the lab for a valid  reason.
- and you need to provide evidence for this reason (doctor's note if you were sick, Dean's excuse if you are planning to miss a lab in order to participate in a valid event).

If the reason for your absence is such that:
- you are not sure whether the reason for your absence is regarded as valid enough to warrant a make-up lab, or/and
- you are not sure what piece of evidence you are supposed to give:
then ask Roger Haar, haar@physics.arizona.edu. He is the one who decides this, not me.
If you know in advance that you are going to miss a lab, let me know by email, as well as Roger Haar.

Give said evidence to me during our lab session, as soon as you have it. 

The make-up lab does not take place during a different day on the same week you missed the lab, and it is not about the same material, either. It is an entirely different lab, which takes place at the end of the semester, usually the week after the lab final.
Although the work you will do during lab-time is the same, the type of assignment and the number of points that the make-up lab is worth varies, depending on whether the lab you missed was a for-worksheet-lab or a for-lab-report lab.

Also, note that only one missed lab may be made-up, i.e. the make-up lab cannot count for more than one lab.

Ladder problem

Below are snapshots of what we did during the discussion session on the ladder problem:

Clarifications for lab report 6

Worksheet pages to be handed in:

These are pages 73-75 (the template may be saying something different, from last semester).

Clarifications for lab report 5

Mistake in the template:

What was originally in the template should be changed to what is highlighted below:

GRAPH 1: Centripetal force vs radius

You must have three different curves on this graph, for the different values of the radius indicated p.65.

Next to each curve, indicate the corresponding value of the radius angular velocity.

GRAPH 2: Centripetal force vs angular velocity

You must have three different curves on this graph, for the different values of the angular velocity indicated p.65.

Next to each curve, indicate the corresponding value of the angular velocity radius.

Clarifications for lab report 4

Clarifications for lab report 4

1) Histograms

DO NOT USE EXCEL TO GRAPH THE HISTOGRAMS

Excel can do bar graphs, but they are not histograms. Draw the histograms by hand.
First choose a scale for your x axis (like you would for any other x axis)
Then choose a bin size; all bins must be the same width.

2) Averages

The averages you need to take are those of the "deltas", of the changes (in momentum or kinetic energy).

3) How to get the standard deviation algebraically is explained p.100 of your lab manual.

4) How much data must I use for each histogram?
At least the 15 lines on each page. Graph together the data corresponding to when the two carts had the same mass, and when the two carts had different masses.

5) What I explained in lab about the histograms and how to use them...
...in pictures! These are the snapshots of the board:

This is what each of your 4 histograms should look like, i.e. all that they should have on them (and it doesn't matter how high you draw the error bars, which are horizontal in this case):

Recall the definition of Delta:

This is what your error bars should look like or not, i.e. roughly how wide they should be compared to your histogram, so you can troubleshoot them. If yours look wrong, first check that you graphed them correctly, one standard deviation to the left of the average, and one standard deviation to the right; if that doesn't fix things, check your calculation of the standard deviation.

  

 And finally, once you've got the error bars, this is how to tell whether your data says that the momentum / kinetic energy was conserved in the collision at stake (the vertical line represents the y axis, i.e. at x = 0):

 

I hope that makes everything clear, but if you have further questions don't hesitate to email me ;-)

Clarifications for lab report 3

Clarifications for lab report 3

How to find the acceleration that you graph need to graph for graph 2 and 3. 

 

  VERY IMPORTANT.

 

Use the times and distances that you measured in the equation: d = 1/2 a t², solved for a.

Do NOT use Newton's second law to find this acceleration: if you did, your graphs would not tell you anything about whether your experiment confirms that law or not, so your graphs 2 and 3 would be meaningless. They are meant to allow you to check that the relationship between the actual accelerations, that is the accelerations measured experimentally, and the actual masses or applied forces, is indeed Newton's second law. So it is CRUCIAL that what you graph in graphs 2 and 3 be these actual accelerations; and those you find by using the actual times and distances that you measured, and the equation d = 1/2 a t².

Lab manual pages

No, you do not need to hand in the pages from the lab manual.

 

When finding the acceleration from graph 1, how can I make sure that I'm doing it right, ?

You can't be 100% sure... but 99% you can. Do the practice examples at the bottom of:

http://physicslabssdeclark.blogspot.com/2012/10/how-to-find-experimentally-value-of.html 

If you're getting them right, it seems you know what you're doing ;-) If not, go over the material on that webpage.

 

 

THE MAIL ROOM

THE MAIL ROOM

If you really must hand in a lab report late:

- don't email me to ask me what to do. Read this instead:

- You will lose points (-10% up to 4 hours late, -25% up to 24 hours, -50% up to 48 hours, too late after that).
- email me a scan of your report as soon as possible; any legible pictures are fine, or you can convert your doc file to pdf online, for instance here: link. Do NOT send me documents in a recent word format (I'm still running XP! What can I say I love XP.)
- Your report will be considered as handed as soon as: I receive by email a copy I can open AND your doc file is submitted into the D2L dropbox, whichever of those two events occurs LAST.
- hand in the paper copy in my mail box, which is in the mail room, PAS 254. It is open during office hours and looks like this: