Physics problem - Page 2

Blackmane · 03-08-2004, 03:45 AM

To support what mariolover is saying:
Of course throwing 100 marbles would be different than 1, but I bet you could throw 3 marbles the same distance because you have a lot of energy and momentum in your throw, but not all of it can be taken by the single marble. A bow is similiar: Of course trying to fire 100 arrows wouldn't work, but 3 arrows get almost the same force as 1 because it builds up an enormous amount of potential energy, but in the release, it releases a lot of that energy away because it can only give so much to one arrow. The string will only move an arrow so far, but it has enough energy leftover to fire off several more arrows and releases that through vibrations, heat, etc.

Therefore, add two more arrows to the system and you have the same force in each arrow, and less energy released in different ways.

Canyarion · 03-08-2004, 09:13 AM

Still doesn't make sense.

Of course, when there is a max speed for the arrow (because of the air resistence thingy).... but then it would be useless to use all your strength when firing arrows. If what you say is true, you might as well fire at 1/3 of max strenght.
And I know that max strenght DOES matter.

I'll ask on an archer forum if that exists.

Kitana85 · 03-08-2004, 11:09 AM

Dude, have ANY of you actually done archary?

Physics aside, its freaking hard to balance the three arrows to shoot them symataniously...
The marble senario is irrelevant as you arne't "heaving" the arrows, so the extra weight doesn't matter.

Neo · 03-08-2004, 11:11 AM

Quote:

Originally Posted by Canyarion

No it's just impossible, where would the energy go?

It just doesn't make sense...

It goes into your arm that you're holding the bow with mostly. That's part of the reason why you have to keep it straight and rigid.

Dyne · 03-08-2004, 12:24 PM

The string isn't straight when it's pulled back, is it? I think that's the confusing part. It'd be like...

<
| <
<

Arrow one and three wouldn't have as much force, because they wouldn't be centered. But, I don't think it makes a difference.

DimHalo · 03-08-2004, 02:39 PM

i think all three would have the same force if you were able to balance all three arrows to shoot at the same time and angle

Happy Dance · 03-08-2004, 02:44 PM

they'll have the same force ..... but lower then only 1 arrow

thatmariolover · 03-08-2004, 03:13 PM

Quote:

Originally Posted by Canyarion

But let's say you're throwing marbles. If you only throw 1 marvel with all your strength, it goes so far you can't even see where it lands.
But if you throw a BAG OF marbles (let's say 100 of them) with all your strength, you won't be able to throw it farther than 10 meter.

That's actually a good example of where your thinking is going wrong. You keep bringing up other factors into it. We're just talking about sheer strength. Sheer force behind the arrows.

A big bag of marbles has a lot of surface area to catch air resistance, which slows it down. Where as, if you threw 5 marbles, they would go similar distances because they're all getting the same amount of air resistance (virtually nothing). The only change would be where the marble left your hand (since a hand isn't exactly even) and what trajectory you sent the individual marbles.

Kitana, you're talking about the difficulty of balancing arrows. We're not calculating that. We're calculating the effects of 3 arrows being shot if they were perfectly balanced, like jeepnut's slave said.

Crono · 03-08-2004, 03:33 PM

Quote:

Originally Posted by Happy Dance

yes... but the first
squirrel will sotp some of the force of the train

so mass matters =P

But the squirrel's mass is irrelevant (sp) to the train's mass. It's like your mass compared to the Earth, according to physics laws, you are also "pulling" the Earth (equal reaction for every action), so if you went 5 000 km into space you would still be pulling the Earth, but your mass compared to the Earth's makes it irrelevant.

If a train with a mass of 40,000 kg hits a squirrel that ways like.. .5kg ... then you won't notice the difference. If the object it hit was much bigger, then you'd see the difference.

If each arrow weighs say... 0.1 kg (probably less than that, or maybe not, but whatever), and the bow weighs 2kg, then the mass of 3 arrows becomes insignificant to the force put out by that bow (F=ma).

Dark Samurai · 03-08-2004, 03:38 PM

Quote:

Originally Posted by Kitana85

Dude, have ANY of you actually done archary?

Physics aside, its freaking hard to balance the three arrows to shoot them symataniously...
The marble senario is irrelevant as you arne't "heaving" the arrows, so the extra weight doesn't matter.

I agree, marbles arent the same as arrows.

Wouldnt be like this?

|<-/-- = 1/6 power
<-(-- = 2/3 power
|<-\-- = 1/6 power

because the initial arrow would be ahead of the rest of the arrows. maybe, im just guessing

Crono · 03-08-2004, 03:40 PM

Quote:

Originally Posted by Dark-Samurai

because the initial arrow would be ahead of the rest of the arrows. maybe, im just guessing

If there is no target in range, they will all hit the ground at the exact same time (if they are all shot at the exact same time).

bobcat · 03-08-2004, 03:57 PM

Wouldn't the centre of the string have the most force?

So the middle arrow should go faster than the top and bottom one i'd imagine.

Common sense

Dark Samurai · 03-08-2004, 04:00 PM

Quote:

Originally Posted by bobcat

Wouldn't the centre of the string have the most force?

So the middle arrow should go faster than the top and bottom one i'd imagine.

Common sense

thats what i said

thatmariolover · 03-08-2004, 05:18 PM

Quote:

Originally Posted by Dark-Samurai

thats what i said

And indeed, it's right.

Dyne · 03-08-2004, 06:28 PM

Quote:

Originally Posted by Dyne

The string isn't straight when it's pulled back, is it? I think that's the confusing part. It'd be like...

<
| <
<

Arrow one and three wouldn't have as much force, because they wouldn't be centered. But, I don't think it makes a difference.

That's what I said way up there.