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neveax

Help with physics, build something that jumps

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Hi,

I'm in gr. 11 physics, for a project, we have to build some kind of jumper. The "winner" is one that jumps the highest with the best weight/height ratio. Compressed gas, rockets and propellers are not allowed. Anything else is fine, like springs/elastics, I think magnets are allowed but I can't think of any way to make the whole system jump. It has to jump, not fly. I really can't think of any, and my idea is really complicated and I have no idea how I'm even going to guild it. Any ideas?

 

Thanks.

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For a few years a 'robot olympics' was run in UK in which research students, engineers and a few families built contraptions to run a sprint race on legs, swim across a pool using 'animal-like' propulsion and do long jumps and high jumps. The event was filmed by the BBC and there may still be some information about it on the internet.

 

As I recall the best high jumper was a small thing a few inches long that looked like it was made from rubber bands and lollipop sticks.

 

The principle of the design was to arrange the sticks in a diamond shape so that all four of the corners had strong, flexible hinges. The diamond could be pushed or pulled flat (ie with one pair of opposite hinges pulled together and the other opposing pair as far apart as possible). Now, if a strong spring or elastic material is attached to the hinges that are going to be pulled far apart they will want to snap back into the diamond shape and in so doing they push the other hinges outwards and the whole thing hops.

 

A word of warning; you can end up with a lot of energy in this thing. If one of the sticks or hinges breaks it could have your eye out. Getting strong enough but light enough materials will be your first challenge. Wood is a good starter as it often craks before snapping which releases some of the energy and is a little safer.

 

The other challenge is how to keep the thing folded up and ready but not to jump until it is in the right position. If you can make that work, you'll have earned your prize.

 

NB I the robo Olympics the 4" high winner jumped over 6 feet. The same group made a larger version about a foot long - it came second. Small is beautiful.

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I searched for robot olympics, but I couldn't find any info on the winners/models. I did find out it's also called the "techno games", but that's about all the useful info I can find. Do you know where I can find a picture of it?

 

Thanks.

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What about a sort of upside-down catapult?

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The entire system has to jump? Or can you have something on the ground, and something fly into the air?

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Do you just have to build the device or do you need to explain how it works and guess how high it might go? It doesn't seem like there is much physics in just building the thing, engineering yes. If I were your teacher you would be explaing the concepts behind how it works and how high you think it will go.

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Get a rod, a flat rectagular piece of materal (be sure it is not heavy), two springs and some glue or tape. Tape the rod to each of the two springs. Then, do the same to the piece of materal. You then push down the rod and let go, hopefully the whole thing bounces.

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Sorry for the late reply, took me a week to find something useful. The entire system has to jump, from the floor/ground up. It just has to jump, no explaination needed. I found this and it's REALLY good. The site is gone now, but it's a good thing I saved a copy of the video before it disappeared.

 

http://72.14.207.104/search?q=cache:wasFoS6IV18J:www.newlandhouse.co.uk/Detail/Artetc/Dt/Imagetechno/techno01.html+%22techno+games%22+rana&hl=en&gl=ca&ct=clnk&cd=1

 

Here's a link to the video:

http://rapidshare.de/files/14613779/mov07123.mpg.html

 

I also attached it to this post as an attachment. I was hoping for the site to return before posting but it seems like that's gone forever now. Any help would be appreciated.

 

Thanks!

mov07123.zip

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What about a sort of upside-down catapult?

 

That is what I thought immediately.

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That is what I thought immediately.

 

Yeah, i'd say that sort of thing is the best idea! If you could use electro magnets you could put a pulse through it to propell it surely?

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By "jump, not fly," I assume it is meant that it has to propelled by physically pushing off the ground only. (If not, you could just have a leaky helium balloon. It will go very high relative to its weight before it comes down again...) Hence, any kind of maglev thing would be cheating, since you're applying continuous force in the air. More importantly, though, it wouldn't even work, because you'd have to be repelling from magnets on the ground, which means the whole contraption wouldn't be jumping.

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