A guy is determined to spray the entire surface of the earth with a weed killer including the oceans etc.
It takes 10 seconds to spray 1m^2, how long will it take to spray the whole world?
The radius=6370km
Formula for surface area= 4 x pi x r^2
The answer is 1.62 x 10^8 years
Geometry sphere question, please help?
2018-09-10 1:11 am
回答 (3)
2018-09-10 1:35 am
✔ 最佳答案
SA = 4πr^24π(6370km)^2 = 5.099 x 10^8 km^2 = 5.099 x 10^14 m^2
So 5.099 x 10^15 sec
Divide by 60sec/min, 60min/hr, 24hr/day
= 5.90 x 10^10 days
Let's use 365.25 days/yr.
1.616 x 10^8 yr
2018-09-10 1:19 am
You have the formula for the area. Plug in the radius, in meters, to get the area in m^2. 1 km = 10^3 m, so r = 6.370 x 10^3 km = 6.370 x 10^6 m.
You know it takes 10 seconds to spray each m^2, so multiply the number of m^2 by 10 to get the number of seconds.
I'm not sure where your question is here. You have all the formulas. What did you need help with?
You know it takes 10 seconds to spray each m^2, so multiply the number of m^2 by 10 to get the number of seconds.
I'm not sure where your question is here. You have all the formulas. What did you need help with?
2018-09-10 1:51 am
It's not a practical question. The assumption is that the Earth is a smooth-surfaced sphere. Rough surfaces like mountains and waves increase the surface area. The Earth is also not a perfect sphere.
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