- #1
asifion
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- Homework Statement
- A mad engineer builds a cube, 2.5 m on a side, in which 6.2-cm-diameter rubber balls are constantly sent flying in random directions by vibrating walls. He will award a prize to anyone who can figure out how many balls are in the cube without entering it or taking out any of the balls. You decide to shoot 6.2-cm-diameter plastic balls into the cube, through a small hole, to see how far they get before colliding with a rubber ball. After many shots, you find they travel an average distance of 2.8 m. How many rubber balls do you think are in the cube?
- Relevant Equations
- not sure but: N/V=p/(k_B*T)
pV=nRT
V/N = distance between atoms?
So, I was thinking that the total volume of the cube divided by the number of atoms (or rubber balls) should intuitively give the average distance between each ball.
What I did was:
N = number of balls
D = avg distance between balls
(2.5)^3 / N = D
(2.5)^3 / D = N
D = 2.8 - 2 * radius (I'm assuming the given average distance is from center to center of each sphere)
2.5^3/(2.8-.062) = 5.7 balls
What I did was:
N = number of balls
D = avg distance between balls
(2.5)^3 / N = D
(2.5)^3 / D = N
D = 2.8 - 2 * radius (I'm assuming the given average distance is from center to center of each sphere)
2.5^3/(2.8-.062) = 5.7 balls
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