jollyhawley

I'm trying to get across to my students that if a projectile is thrown horizontally and the same kind of object is dropped from the same height and at the same time, both objects will hit the ground at the same time (neglecting air resistance). I had them put a washer on a ruler, and hit another washer off the table with the ruler- so that have one washer drop and the other one be hit at (hopefully) the same time. A few of them weren't convinced. Do you have any ideas for demonstrations or videos to watch to help prove this? Thanks.

Thanks for the suggestions... I hadn't thought about using acetone with the dry ice- good to know! I thought about using methanol for the flame tests as I've heard that it is better suited for that. However, I've also heard that it's very dangerous to burn methanol because the flame is clear. That scared me away from it- I don't want a liability on my hands. What has your experience with it been?

I'm a science teacher buying supplies for this year and was wondering how much of a difference 95% ethanol would be from pure. I am planning on primarily using it for flame tests. I am also going to use it as a substitute for liquid nitrogen by putting it in a beaker with dry ice. I suppose it might not be quite as cold as pure ethanol, but that's the only drawback I can think of. I almost feel silly posting a question like this, but I thought it wouldn't hurt to ask- maybe I'd get some insight. If any of you have any suggestions on where to buy ethanol, that would be great too. The best price I've found so far is at carolina.com. Thanks.

They're not polarized lenses... I just tried it. All putting the two of them together does is making the color tint darker. Rotating one relative to the other makes no difference.

I was cleaning out my classroom closet today when i stumbled upon a package of 28 small (~1 cm in diameter) glass discs. On one side they act as gold tinted mirrors. When I look through them, it shows objects as different shades of color depending on how the light hits it. The outside of the package says "Spectra-Physics Optics". Any ideas on what they are? Thanks!