1. hi every one ,

I am a fresh man engineer and am taking an NGN course " introduction to engineering and computing" . one of the course major requirments is buliding a project " simple one " , my project that i was assigned to do is to design a structure made of toothpicks that can float and carry a dropped filled " reguler 500 ml" water bottle that is dropped from a height of 25 cm ..

the projects contrain is weight .. the lightest is the best .. and also we should use only the superglue and tooth picks ..

my question and i wish you could help me as expertise ...

i was thinking of buliding a structure which is a net of toothpicks "rectanguler" and each edge is supplied by a upside down pyramid shape ...

so i wonder if it will work , if not what do you suggest as the best shape or structure that can do the jop .. the less tooth picks the best

i will appreciate your assistance , and please if you provided me by any idea tell me your full name and profession so i can ,appropriately, reference you in the project report ..

2.

3. I don't think the inverted pyramid would be very stable, and it would want to tip over and ship water when you drop the bottle of water into it. Also, it's not particularly efficient. For maximum flotation, you want to displace more volume. Remember that the buoyant force is equal to the weight of water displaced. I think a hemispherical shape would maximize the volume per surface area, but you may need to modify that a little bit to be able to withstand some rocking without taking on water. You will probably want to end up with something resembling a real ship or boat.

4. thanks alot for your comment . but the problem is that such a shape couldn't be easly constucted by toothpicks , even if i did it will be weak ..
by the way , how can i use the height and the bottle's wight to compute the force the bottle will exert on the ship when it hits it .. ?

5. sorry another thing ! , i thought of a stucture that is a half cylineder . do you think it will be effecient ? constucting a cylinder is way easier than hemispherical shape ? ...

waiting your response , and again thanks alot for your assistance ..

6. If your toothpick assembies must be water-tight, you may end up with more weight in glue than wood.

Take advantage of a toothpick's taper. You could build a lot of buoyant cones... is that in line with the upside down pyramids you mentioned?

Carrying a bottle of water sounds like a trick problem. Of course it floats all by itself in water. Must you "carry" it above water?

7. Originally Posted by sara azzam
how can i use the height and the bottle's wight to compute the force the bottle will exert on the ship when it hits it .. ?
The weight of a 500 ml bottle of water is half a kilogram. In order to support that weight statically your boat will have to displace an equal weight of water i.e. 500 milliliters. In addition it will have to absorb the energy of the falling weight. Since the bottle is dropping from a height of 25 centimeters, then the potential energy is mgh, where m=0.5 kg, g is 9.8 meters/sec/sec, and h is 0.25 meters. So, that is 1.225 joules. This energy will do work in submerging your boat, which will be an integral of the buoyant force times the depth of submergence.

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