August 10th, 2009, 04:01 AM
ok . i need to kno which type of card would travel further (being thrown by hand) - cardboard or plastic .. and why ? is it because of the surface area ? or mass ?
also do any of these have an effect - gyroscopic effect, bernoulli principle ?
ASAP
xD
for same size cards the higher density one will go farther.
Whats the hurry, you entering a card thrownig contest?
It depends greatly on the aerodynamics and rotation of the cards, not just the mass.
you have to assume that the only variable is the composition of the card, every thing else being constant, the stiffest more massive one will go farther.
Go try it.
BYE
A reduction in air resistance will have a big effect on the answer to this problem; as fizzlooney stated, the density. You can find the density of the cards using the following method: measure the dimensions of the card (you only need to measure the base and the height, as the length is equal and would require too little of an error value). Than multiply these figures to recieve the area (which will be equivalent to the volume in this case, as, again, the length will have little effect). Finally, take the mass of the cards and divide them by the previous area you recieved. This will give you the density to I'm sure over 99.99% accuracy. The card that recieves a higher quotient value (which is equivalent to the density) will more likely than not go farther.
August 10th, 2009, 02:21 PM
The distance thrown is going to depend on the initial velocity, and the air resistance that causes it to decelerate.Originally Posted by skivvies
For puposes here the air resistance will be approximately the dynamica pressure (times the frontal area. Here
is air density, over which you have no control. The mass of the card is proportional to density. So is the momen of interia about the centroid.
Cards are sufficiently light that the limiting factor on initial velocity is your arm, and not the card, so initial velocity is indepentend of the card.
The kicker is cross-sectional area and here that means area normal to the velocity vector. That is determined by the aspect of the card presented to the air stream. Since you want that to be small you want the card to fly edge-on. To keep the card flying edge on and stable as long as possible you will spin the card and rely on gyroscopic action to keep the card from "fluttering". So the key is providing the maximum angular momentum. From the perspective of the card that means a card with masimum momentum of inertia about the centroid. That in turn means maximum density and maximum size (for fixed thickness the mass goes up as the square of the edge size while the frontal area goes up linearly).
You need the cards to be stiff so as to eliminate structural bending which will increase the frontal area. That probably means a thicker rather than a thinner card. (Tissue paper cards would not be good).
So, use poker cards if you can since they are bigger. Use a new, stiff deck. And spin them vigorously.
so which one wuld go further ? plastic or carboard ? (poker = cardboard?) because it is stiffer and has a greater mass ?
The poker cards will, assuming equal technique. Although, if you are talking about Polyethylene terephthalate than the result might be interesting depending on the status quo of whatever expirement might be conducted. "Stiffer" cards will cut through air molecules easier, and a greater mass per cubic length means less air resistance; feathers for example, which have a very low density can't be thrown very far at all in comparison to high density materials, rocks, for example.
kk ty everyone 4 ur help
Did you listen?
Cardboard --- folded into a paper airplane.
or a cylindrical airfoil. Those things go pretty far.
arent they those things u shoot at ppl to knock em out ? - tom clancey's splinter cell
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