# How are pictures drawn by M.C. Escher breaking the laws of physics?

1. Jan 8, 2007

2. Jan 8, 2007

### Staff: Mentor

Is this a homework problem? If so, I can move the thread to the appropriate homework forum.

Also, what is your thinking so far on this? What laws would be the most ovbious for starters?

3. Jan 8, 2007

### chibichibi7554

yeah, its a hw problem. i really have no idea because i pretty much don't really know any laws...

4. Jan 8, 2007

### dontdisturbmycircles

Sure you do! Physics is just the study of nature. You intuitively know laws like objects that have more mass are harder to push, you just don't know the equations for them yet. What grade are you in right now? Is it possible for someone to be standing upright one side of a flight of stairs and have another standing upright on the other side of the flight of stairs? Why?

5. Jan 8, 2007

### chibichibi7554

lol im in 11th grade 7 honors physics! I know that its not possible but I dont know why. I can't just say gravity lol but thats the only thing I can think of.

6. Jan 8, 2007

### dontdisturbmycircles

Ok, lets think about it this way. What provides the gravity that holds you down on a flight of stairs? The Earth or the stairs?

7. Jan 8, 2007

### chroot

Staff Emeritus
What can you say about Waterfall and the conservation of energy?

- Warren

8. Jan 8, 2007

### dontdisturbmycircles

That's a really good one, chroot.

9. Jan 8, 2007

### chibichibi7554

Well I am thinking its both considering everything with mass has gravity. But ofcourse the earth has a lot more mass. I didnt even look at the picture that way. I guess I get the point but I don't know what law that would pertain to or how to put it into the words. The best I can come up with is that the picture is wrong because the thing with the bigger mass, the earth, has more pull than the stairs do on the people so all of the people should follow that in how they are walking on the stairs but some of them don't....

10. Jan 8, 2007

### chibichibi7554

we just took a test on that today (one i failed btw but none the less...) you cant destroy or create energy but I dont see how that has to do with the waterfall being all weird and not making sence how it falls...

11. Jan 8, 2007

### chroot

Staff Emeritus
If the waterfall flows forever, turning the waterwheel all the time, and has no external source of energy, what can you say about energy?

Surely, people inside the building could be using the waterwheel to run machines, mill flour, or do any other kind of work they wished to do...

- Warren

12. Jan 8, 2007

### dontdisturbmycircles

try this, or if you can't try this, at least think about it. Take two bottles, fill one, and connect them with a hose. If you tip them both upside down so that they are side by side and the hose is hanging below, how far do you have to lower the empty bottle before water starts transfering to the empty bottle? I can tell you right now that you can't get the water to go up higher than it started. Why? hint: Potential energy/conservation of energy. Do you have a textbook that you could review from?

13. Jan 8, 2007

### chibichibi7554

i dont have a book but i know what ur saying dontdisturbmycircles i guess.

and chroot. I sort of understand, but like... so the energy from the water is being transfered into wheel... to turn but the wheel is pushing the water too. But I guess a lot of the energy from the water turning the wheel also goes a lot to turning other gears and stuffs

14. Jan 8, 2007

### chibichibi7554

I still have no clue about the other ones

15. Jan 8, 2007

### dontdisturbmycircles

At the top of the waterfall, the water has a certain amount of energy. Namely, it's potential energy, given by

$$E_{p}=mgh$$

Where $$E_{p}$$=potential energy
m=mass
g=gravitational acceleration, ~$$-9.81m/s^{2}$$ on earth's surface,
and h = the height above the surface, or above the "reference point".

So what happens when the water falls onto the wheel? Where does the water's energy go? Does the water do WORK on the wheel? How much energy would it take to raise the water back to it's original height? Do you see the problem?

Hint:conservation of energy! In order to raise an apple above a table so that it can exert 10N of force on the table when it falls, you must use 10N of energy raising the apple to that point if you pick it up from the table.

If you don't have a textbook, what exactly have you gone over in class? review your notes, I mean, you had to have learned something that you can apply here.

Last edited: Jan 8, 2007
16. Jan 8, 2007

### chroot

Staff Emeritus
If the waterwheel spins forever, without any external source of energy, then it's "creating" energy all the time -- which is a violation of the conservation of energy.

- Warren

17. Jan 8, 2007

### chibichibi7554

yeah now i do see the problem with that one

18. Jan 8, 2007

### chibichibi7554

how does belvedere ?