[QUOTE=WhyNot]
Does that sort of ratio still hold for this huge sort of height, or is the bounce height based on the speed when it hits the ground?
[/QUOTE]
Bounce height is only based on speed when it hits the ground. So, it won’t bounce any higher then if you throw the ball down real hard, assuming you can throw a b-ball into the ground at 40 MPH.
[QUOTE=WhyNot]
So how high would it bounce, assuming we’re doing this in the desert, on smooth rock, from a helicopter at the height of the Empire State Building (so it bounces more or less up, not ricocheting off anything.) My eyeball estimate of the bouncing soccer ball with the kids seems to show about 1/3 to 1/2 bounce back (depending on how well inflated the soccer ball is) with short distance bounces. Does that sort of ratio still hold for this huge sort of height, or is the bounce height based on the speed when it hits the ground?
I have the sinking feeling I once knew how to figure this out, but pretty much all the maths I ever learned leaked out of my brain just after Finals.
[/QUOTE]
The coefficient of restitution for an NBA ball is approximately .79-.85 (cite), which is just a fancy way of saying that the ball retains about 80% of it’s speed after bouncing off the ground. Using 50 mph as the terminal velocity and neglecting air resistance, I calculate that the ball will bounce 53 feet up in the air. That’s quite a bit more than what any regular human can accomplish, but I don’t think it will damage the ball.
[QUOTE=Jake]
But those windows don’t open, do they? How did he jump out of a window that doesn’t open? I also understand that they don’t break easily either.
[/QUOTE]
I don’t know about today, but the building originally had windows that opened.
I’ve actually tried to throw pennies off the observation deck of the ESB. My brothers and I did it when we were teenagers. We found out just what people are saying. You practically have to be Roger Clemens to get a penny past the wider tiers. I don’t know how anyone could do it with a basketball.
The pennies we threw would disappear from sight fairly quickly so couldn’t really tell if we got any to the ground. We’d heard that a penny hitting the sidewalk would make a crater and we wanted to try it out.
[QUOTE=Stranger On A Train]
The real problem is that it has to go through an infinite number of steps, each one half the distance of the last. No matter how many steps it takes it still has an infinite number of steps to go, so no matter how close it gets to the ground, it never quite touches it. This is what keeps the ball from exploding like the Hindenberg, and is coincidentally also the principle by which bumblebees fly.
This concludes today’s Science Misinformation Moment.
Stranger
[/QUOTE]
The problem is that it is on a conveyor belt that goes as fast as it does. This precludes it from moving at all; it simply hangs in midair.
[QUOTE=Diogenes the Cynic]
I’ve actually tried to throw pennies off the observation deck of the ESB. My brothers and I did it when we were teenagers. We found out just what people are saying. You practically have to be Roger Clemens to get a penny past the wider tiers. I don’t know how anyone could do it with a basketball.
[/QUOTE]
But a basketball bounces better than a penny. The ball will still have some horizontal velocity, and if it’s going fast enough it could clear that first tier and then fall to the next tier.
[QUOTE=DSYoungEsq]
I suspect that a basketball can go faster through the air than 56 mph. As noted, soccer players can kick soccer balls at speeds exceeding 65 mph.
When calculating terminal velocity, what is done about spin? Spin presumably has an effect on how fast the ball can go through the air…
[/QUOTE]
Spin would only increase the lateral velocity of the ball. If you put a lot of spin on it you might end up scuffing it but you aren’t going to rupture it.
[QUOTE=DSYoungEsq]
I suspect that a basketball can go faster through the air than 56 mph. As noted, soccer players can kick soccer balls at speeds exceeding 65 mph.
[/QUOTE]
But that doesn’t directly relate to terminal velocity. You can propel a ball much faster then terminal velocity by throwing it out of a plane, but once you let it go it will slow down even in free fall. Once you drop it off the building the only forces acting on it are gravity and drag. Even if you shot it out of a cannon from the top of the ESB it would slow down before hitting the ground.
I suspect that you are right, however terminal velocity doesn’t mean maximum possible velocity. The terminal velocity of an object is the maximum speed the object will reach while falling freely through the atmosphere - the point at which the drag of the atmosphere balances the gravitational acceleration.
On preview… also what Telemark said…
[QUOTE=DSYoungEsq]
I suspect that a basketball can go faster through the air than 56 mph. As noted, soccer players can kick soccer balls at speeds exceeding 65 mph.
[/QUOTE]
Right, but that’s a human force, not terminal velocity. Many pitchers can get fastballs over 100 mph (or so I’ve heard), but that’s irrelevant; the issue here is how fast gravity will make the basketball go.
[QUOTE=Stranger On A Train]
The real problem is that it has to go through an infinite number of steps, each one half the distance of the last. No matter how many steps it takes it still has an infinite number of steps to go, so no matter how close it gets to the ground, it never quite touches it.
Stranger
[/QUOTE]
What if Achilles were dropped fIrst?
[QUOTE=Diogenes the Cynic]
I’ve actually tried to throw pennies off the observation deck of the ESB. My brothers and I did it when we were teenagers. We found out just what people are saying. You practically have to be Roger Clemens to get a penny past the wider tiers. I don’t know how anyone could do it with a basketball.
The pennies we threw would disappear from sight fairly quickly so couldn’t really tell if we got any to the ground. We’d heard that a penny hitting the sidewalk would make a crater and we wanted to try it out.
[/QUOTE]
Heyyyyyy, wait a minute. What were the dates on those pennies? Because several years ago, a friend of mine was killed by a falling penny right outside the ESB. We looked up and saw a guy and his brothers up there on the roof. Roseville, MN, huh?
[QUOTE=David Simmons]
What if Achilles were dropped fIrst?
[/QUOTE]
Achilles is dead, silly. He caught his ankle on a handrail on the Eiffle Tower while horseplaying around and fell to his dead in Paris, leading to the common misperception that he was killed by Paris. Paris, of course, was totally innocent of all charges except kidnapping the Queen of Sparta, which is really not a very wise thing to do considering that the Spatans were such badasses that they had a Swiss Army Knife design named after them, but so it goes.