pic: Our machine is too fast...

[Arkorobotics]

loading photo ...

[Andrew Blair]

Did somebody put a bullet through that windshield?? Maybe you should consider the neighborhood before setting up a robotics shop...

[Greg Perkins]

this is deffinatly a fake, theres no way a foam ball can shatter a windshield that badly. the root of the impact is way smaller than the size of a poof ball. nice try, funny lol

[Tom Bottiglieri]

Originally Posted by Greg Perkins

this is deffinatly a fake, theres no way a foam ball can shatter a windshield that badly. the root of the impact is way smaller than the size of a poof ball. nice try, funny lol

Uh...

Duh?

[dlavery]

this is deffinatly a fake, theres no way a foam ball can shatter a windshield that badly. the root of the impact is way smaller than the size of a poof ball. nice try, funny lol

Ahem. Care to make a little wager on that?

Before anyone volunteers too quickly, I would remind you about the group of professional engineers that adamantly proclaimed that there was absolutely no way that a piece of lightweight foam could ever punch a gaping hole in a carbon-carbon reinforced panel on the leading edge of a wing.

I am not bringing this up to be maudlin. Rather, it is done to illustrate the point that we need to be very, very careful when making blanket statements. As engineers, we should understand that physical phenomena are typically bounded by certain parameters of performance. When we make assertions regarding those phenomena, it must be done in the context of the parameters relevant at the time. We must take care care when discussing these phenomena not to make statements such as "event X is always true" when what we really mean is "event X is always true when condition Y is true, otherwise it isn't." Otherwise, imprecision and inaccuracy will inexorably find their way into our communications. When that happens, we run the risk of losing the trust of the public and being perceived as an error-prone, lackadaisical profession.

-dave

[Wetzel]

Originally Posted by Greg Perkins

this is deffinatly a fake, theres no way a foam ball can shatter a windshield that badly. the root of the impact is way smaller than the size of a poof ball. nice try, funny lol

I'm sure the foam ball could shatter the windshield.
Can a box of tissues decapitate someone?

Dave, you beat me too it.

Wetzel

[KenWittlief]

unfortunately that windshield is characteristic of what happens if you dont wear your seat belt.

That may not be what happened to this car, but when it happens thats about where your face hits :c(

[Arkorobotics]

Oh come on! You've got to be kidding! There is no way in this world that a foam ball did that damage. When the people came to rip up the car and sell it (for scrap, by the way this car is on it's way to death row, we need to rip it up and sell the parts) we had to take a sledgehammer to it (breaking the windshield) and it did little damage of a small little hole and a huge crater. Plus there are other cracks in other places.


P.S. - no "KenWittlief" nobody was in the car and no one was hurt during the "destruction", but ya I bet you can seriously get killed if you don't have your seat belt on and you will create a larger hole than that and probably fly throught the windshield.

[Wetzel]

Originally Posted by Arkorobotics

Oh come on! You've got to be kidding! There is no way in this world that a foam ball did that damage.

We actually spent a good deal of time talking about the physics of an accident in my trauma class this week and last. F=ma. You can apply as much force as you want if you can control either the mass or acceleration. When you negatively accelerate the ball by hitting the windshield, you transfer that energy to the windshield. The ball may not have all that mass, but you fire it fast enough and it will shatter that windshield.

Wetzel

[Arkorobotics]

Originally Posted by Wetzel

We actually spent a good deal of time talking about the physics of an accident in my trauma class this week and last. F=ma. You can apply as much force as you want if you can control either the mass or acceleration. When you negatively accelerate the ball by hitting the windshield, you transfer that energy to the windshield. The ball may not have all that mass, but you fire it fast enough and it will shatter that windshield.

Wetzel

Well your acceleration better be reallllyyyyy high up! but doesn't material count? and compression?

[Wetzel]

Originally Posted by Arkorobotics

Well your acceleration better be reallllyyyyy high up! but doesn't material count? and compression?

F=ma. The force will equal the mass of the ball times the acceleration.
Acceleration is the rate at which an object changes its velocity, so the compression will lower the acceleration by some amount. By slowing the ball over an extra 2 inches, you have a smaller acceleration. With a smaller acceleration you have a lower force.

All that means is you need a higher starting velocity.

Wetzel
PS: If someone who has taken actual physics rather than physics of a body in an accident and can explain it better please do.

[Alekat]

Originally Posted by Wetzel

F=ma. The force will equal the mass of the ball times the acceleration.
Acceleration is the rate at which an object changes its velocity, so the compression will lower the acceleration by some amount. By slowing the ball over an extra 2 inches, you have a smaller acceleration. With a smaller acceleration you have a lower force.

All that means is you need a higher starting velocity.

Wetzel
PS: If someone who has taken actual physics rather than physics of a body in an accident and can explain it better please do.

Sounds to me like you did a great job. As long as you can establish that your poof ball won't have to exceed the speed of light to punch a hole, it is possible.

two things you have to remember from physics:
1. F=ma
2. You can't push on a rope.

[KenWittlief]

what if the foam ball was soaked with water when it hit, and it weighed as much as, oh.. lets say a pumpkin?

[greencactus3]

ooh has anyone tried that? its cold around here for watergames but.

[artdutra04]

Originally Posted by KenWittlief

what if the foam ball was soaked with water when it hit, and it weighed as much as, oh.. lets say a pumpkin?

If we tried that, the ball would probably freeze solid even before it got to the car.