# Homework Help: Stump the science teacher

1. Nov 21, 2004

### Dirkspink

We're doing a science project, and we get major extra credit if we have a question in our project that he can't answer. He told us that his ''weakness'' would have to be physics. So does anyone have some questions i could ask that could stump an eighth frade science teacher? Anything at all?
THANKYOU

2. Nov 21, 2004

### Dirkspink

3. Nov 21, 2004

### Gokul43201

Staff Emeritus
I'm not sure if this is eighth grade material, but you might know about the demo that "proves" that sound needs air for propagation. You put a sound maker (like a ringing alarm clock) in a bell jar that's connected to a vacuum pump. If you start the pump and evacuate the container, the ringing becomes fainter and soon goes away. The "explanation" given is that when evacuated, there's no air in the jar, and hence, no way for the sound to travel.

But if you have a pressure guage connected to the jar, you can find the pressure at which the sound stops being heard. At this pressure, the mean molecular spacing is actually smaller than the typical audible wavelengths. So, then, at this pressure, sound should be able to travel. Yet, you can't hear it. Why ?

4. Nov 21, 2004

### Dirkspink

ok. I like the question, but what is the answer? i need to know to get the A.

5. Nov 21, 2004

### vsage

Finding the effective resistance of odd objects is mathematically simple if you know how to manipulate them the right way. A few years ago someone asked me what the resistance of two opposite vertices of a Hypercube was given each side was a resistor of 1$$\Omega$$. If you are a little clever and know how resistances are added, it's no more than an hour's work.

Last edited by a moderator: Nov 21, 2004
6. Nov 21, 2004

### Physik

Use a quantum mechanics problem. I'm sure he doesn't know many, if any, formulae for it.

7. Nov 21, 2004

### vsage

The catch is I think we have to convince the student how to do the problem too though!

8. Nov 21, 2004

### Sirus

You could also ask him to derive the parallel axis theorem for a three-dimensional mass. That's good fun.

9. Nov 21, 2004

### Physik

He could use an easier QM formula.

10. Nov 21, 2004

### OddThoughts

Here are a couple of simple problems that when people overthink them they are easily stumped.

1. If you have a room that is 100% thermally insulated at a comfortable temperature of say about 70 deg F, then you introduce a refrigerator into the room and it is running with the door open,,, after a long enough time for the room temp to stableize , ,did the temperature of the room decrease, increase, or stay the same as before the refrigerator was there? Why?

2. If you are in a small boat in a swimming pool and there is a bowling ball in the boat as well, and you toss the ball into the pool. Does the water level in the pool raise, lower, or stay the same? Why?

11. Nov 21, 2004

### ek

He's a grade eight science teacher. It shouldn't be that hard to come up with something pretty simple he won't know.

How about asking him what Newton's second law is. He'll say $$\vec{F} = m\vec{a}$$ and you'll say, no, it's actually $$\vec{F} = m \vec{a} + \vec{v} \cdot \frac{dm}{dt}$$

I think that might do the trick. Not hard to understand either.

12. Nov 21, 2004

### Physik

Just ask him to solve a projectile motion problem.

13. Nov 21, 2004

### Dirkspink

again, i love the problems, but i know absolutely NOTHING about QM or any kind of physics, so I need the answer to the problems, but thanks (especially ek)

14. Nov 21, 2004

### Chronos

Place a drop of ink in a jar of glycerin. Slowly stir the mix until the ink drop dissipates. Slowly stir again in the opposite direction and the ink drop will reform. Ask teacher to explain what just happened.

15. Nov 21, 2004

### Dissident Dan

Dirk, you can't just ask for other people to do your homework for you. You also have to pay. J/K.

Seriously, we can provide guidance, but we can't do your work for you. That's life.

16. Nov 21, 2004

### Sirus

Dirk, the best way to find questions (and answers!) that your teacher won't be able to solve is to browse through some of the forums here. The college-level homework help forum will have some challenging questions, most of which we can explain to you so you understand the answer. Answering questions is why we're all here, and there are plenty of hard ones, so start browsing.

Last edited: Nov 21, 2004
17. Nov 22, 2004

### Dirkspink

should have thought of that...thanks

18. Nov 22, 2004

### Raza

we are giving him advice and suggestion

19. Nov 22, 2004

### Dirkspink

what about some laws of physics? I saw a thread with links to a whole lot of them, but i have no clue which ones would be more known than others--the ones my teacher probably wouldn't know. I took a look through through them, but i couldn't tell the hard ones from the common ones.

20. Nov 22, 2004

### Gokul43201

Staff Emeritus
Among the laws, Bernoulli's principle is most misunderstood - especially that it pertains to points along the same streamline.