# Homework Help: Suggestions for a decent experiment i can carry out in a classroom lab

1. Nov 7, 2004

### mac2000

hi can anyone please suggest an interesting, good practical experiment that i can carry out in a classroom explaining a physics concept. Its a project i have to do. any help would be greatly appreciated, thanx

2. Nov 7, 2004

### arildno

Conservation of angular momentum perhaps?
Would an experiment showing this be of interest?

3. Nov 7, 2004

### Claude Bile

You can get lasers from most hardware stores these days for about twenty dollars. Having a laser opens up some nice possibilities, Young's two slit experiment would be an obvious start, but you might want to consider doing an experiment on polarisation (this is easy), or, if your audience is a bit older, doing an experiment on laser 'speckle'.

Claude.

4. Nov 8, 2004

### mac2000

yeah totally any help i can get is great! :)

5. Nov 8, 2004

### ZapperZ

Staff Emeritus
It would help to know (i) the level of physics knowledge of your "audience" (ii) what you have available or at your disposal.

Zz.

6. Nov 8, 2004

### PhysicsNovice

Hello Mac 2000. I am not sure of your audience but the concepts might work and you can gear it to the audience (elementary, junior high, seniors, college, adults, etc.) Some of Newtons (maybe Galileo's) observations on pendullum movement is pretty easy to repeat and keeps some interest. You could have a long string with a ball of some type attached to one end. The other end to the ceiling. swing the pendullum and time the cycle movement. Then you could change the length of the string (several times) and do the same experiment. Plot or discuss the pendullum length to the cycle time of the swing.

7. Nov 9, 2004

### PhysicsNovice

What have you decided to do in the lab experiment? If you have a younger audience a bucket full of water that you spin around in a large circle using your arm is dramatic. Of course the force and momentum of the water in the bucket will keep it in the bucket and not spilling out when the bucket is overhead.

8. Nov 9, 2004

### Phymath

gyroscopic motion of a bicycle wheel on a rope, or turning it over to cause you to start turning in an office chair is pretty long to explain that might make u seem more knowlegdeable plus it looks cool

9. Nov 9, 2004

### arildno

Here's an experiment which illustrates conservation of angular momentum:

1) One smooth table, with a tiny hole smoothly drilled through it
(The table/plate must be smooth in order to reduce friction as much as possible.

2) One long string, with cross area only slightly less than the hole in the table.

3) Two bobs/balls of some metal which can be attached to each end of the string.

THE EXPERIMENT:

1. Draw the string through the hole of the table, and attach the two balls at eith end, so that one of the ball lies on the table (quite some distance from the hole), whereas the other hangs free down the vertical (beneath the table)

2. Give the ball on the table a push to the side, so it starts to move in a circular fashion about the hole.

3) What you should see is the following:
a)The vertically hanging mass should fall downwards and be drawn upwards in a periodic manner.
b) When the mass sliding atop the table at maximum distance from the hole, it should have the lowest angular velocity.
As it is drawn inwards to the hole, it will start rotate faster and faster around the hole, until it reaches some minimum distance from the hole. Then it is drawn outwards again until it reaches maximum distance, and the cycle repeats.

If this sounds interesting, let me know..

10. Nov 9, 2004

### mac2000

yeah sorry guys i should have. I'm doing it for college so quite a decent standard but also it need to be something that i can obtain results from. Sorry should have mentioned that but i appreciate the help im getting :)