Earth comparo thing: the planet and a tennis ball

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twsp86

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Greetings,

I'm working on a sheet of earth's characteristics compared to a tennis ball. If I know the weight of the earth in ounces and diameter of the earth in inches, and the diameter of a tennis ball is 2.7", isn't it simple math to obtain a "scale weight" of the tennis ball? Below is how I'm doing this, but I get a huge number of tons which doesn't seem right. Thanks for any opinions!

Earth weight (approx) =
6,479,034,670,000,000,000,000 tons
x 2000 = 12,958,069,340,000,000,000,000,000 pounds
x 16 = 207,329,109,440,000,000,000,000,000 ounces

Earth’s diameter = 7920 miles = 501,811,200 inches

Tennis ball diameter = 2.7 inches

2.7 / 501,811,200 = 0.0000000053805096 size ratio factor

0.0000000053805096 x 207,329,109,440,000,000,000,000,000

= 1,115,536,263,701,370,624 ounces

Divided by 16 = 69,721,016,481,335,664 pounds

Divided by 2000 = 34,860,508,240,668 tons
 
twsp86 said:
Greetings,

I'm working on a sheet of earth's characteristics compared to a tennis ball. If I know the weight of the earth in ounces and diameter of the earth in inches, and the diameter of a tennis ball is 2.7", isn't it simple math to obtain a "scale weight" of the tennis ball? Below is how I'm doing this, but I get a huge number of tons which doesn't seem right. Thanks for any opinions!

Earth weight (approx) =
6,479,034,670,000,000,000,000 tons
x 2000 = 12,958,069,340,000,000,000,000,000 pounds
x 16 = 207,329,109,440,000,000,000,000,000 ounces

Earth’s diameter = 7920 miles = 501,811,200 inches

Tennis ball diameter = 2.7 inches

2.7 / 501,811,200 = 0.0000000053805096 size ratio factor

0.0000000053805096 x 207,329,109,440,000,000,000,000,000

= 1,115,536,263,701,370,624 ounces

Divided by 16 = 69,721,016,481,335,664 pounds

Divided by 2000 = 34,860,508,240,668 tons
Click to expand...
No...your calculation would be correct if earth was made of rubber and felt and glue (or tennis ball was made water, silicon, etc.)
 
Okay

Thanks for the reply. What I want to do is find what a tennis ball sized earth would weigh compared to the real thing. Any ideas?
 
twsp86 said:
Thanks for the reply. What I want to do is find what a tennis ball sized earth would weigh compared to the real thing. Any ideas?
Click to expand...
You'll need to get a scale factor for volume not length and work with that.
For example, if you double the radius of a sphere, you actually x8 the volume. Weight is directly proportional to volume (assuming consistent density) not diameter.
 
Thanks!

I see what you mean, I'll get back on the game, thanks for your reply!!
 
The density of the Earth is 5.513 g/cm3.

Approximate diameter of a tennis ball = 8 cm

so

Approximate mass of a tennis ball sized earth = 4/3 * π * 43 * 5.513 g = 1477.939 g [edited - had lost that irrational π last time]

A bit more than 3.25 pound-mass (453.6 gm).


 
Last edited by a moderator:
This is great, thanks!!!!

Thank you very much for this, and next time I WILL use a cricket ball!!!!
 
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