How old is the ball?
10 replies (most recent on top)
is the ball LGBTQ and rainbow colored? that may allow it to be perceived as performing better than a standard ball of equivalent size...
Haha. Loving the answers. the creative engineering mind! 😄
This thread made me chuckle...
technically, the ball would never "hit" the ground as there is space between everything (electrons).
Also, the fastest it could possibly travel from its starting point to the ground is instantaneously; therefore, it would not bounce but just immediately come to a state of rest after teleporting from A to B.
Engineers.... It's a trick question. If you look at the second mention of 'it' the antecedent is the ground not the basketball. So how high would the basketball bounce if it doesn't pop the ground? The basketball can never hit the ground because the basketball will burn up before coming in contact with the ground.
So - a NBA basketball is inflated to ~8 psi. In real person units this is 0.55 bar.
Most data I can find state that a basketball will pop if over-inflated by 50-70%, so we're looking at a burst pressure of 0.825-0.935 bar. Let's go for the higher value as it's more fun.
So to raise the pressure in the basketball (assuming no heat is transferred), it has to deform as it impacts, specifically, the volume has to reduce by a factor of 1.7
The work done in compressing gas can be given by:
W=nRTln(V1/V2)
Where we know R (Ideal gas constant), T (temperature in K - call it 17 C or 290 K) and V1/V2 = 1.7
n is a little more tricky - the number of moles of gas. 1 mol of gas takes up 24 l at 1 bar pressure, at 0.55 barg, it will take up 24/1.55 = 15.48 l. The volume of a basketball is ~8.6 litres, so there is 8.6/15.48 = 0.554 mol of gas inside it.
W = 0.554 * R * 290K * ln(1.7)
W = 708.8J
So - we know the energy needed to compress the basketball to it's limit, and the expansion that follows the bounce must release the same amount of energy. - So we can work out the speed with which it leaves the bounce (which is also the speed it went in with):
W = 0.5mv2
Where m is the mass of a basketball (0.625 kg)
v = (708.8J * 2 / 0.625 kg) 0.5 = 46.7 m/s (106.5 mph)
So here I'm going to resort to modelling the air resistance and gravity effects on it:
The maximum height it reaches is 40.45 m That's your answer
The answer is yes
5
Is this an African or European basketball?