In and around volcanos, if it is multiple choice tell me the choices.
The pointy things that hang down from the cave's ceiling are stalactites. (A)
The pointy things that grow up from the cave's floor are stalagmites.
(I imagine wearing shorts and hiking through tall grass in the Summer, and I say to myself "When the Mites go up, the Tights have to come down.".)
Answer:
1.305 * 10⁻¹⁰
Explanation:
The earth disk is circular, hence the area of the earth disk is given as:
![Area\ of\ earth\ disk=\pi r_{planet}^2\\\\but\ r_{planet}=6371\ km=6371000\ m\\\\Area\ of\ earth\ disk=\pi (6371000)^2\\\\a=1.5*10^8\ km=1.5*10^{11}\ m\\\\Area\ of\ earth\ orbit=4\pi a^2=4\pi (1.5*10^{11})^2.\\\\Therefore:\\\\\frac{Area\ of\ earth\ disk}{Area\ of\ earth\ orbit}=\frac{\pi (6371000)^2}{4\pi (1.5*10^{11})^2} =4.5*10^{-10}\\\\](https://tex.z-dn.net/?f=Area%5C%20of%5C%20earth%5C%20disk%3D%5Cpi%20r_%7Bplanet%7D%5E2%5C%5C%5C%5Cbut%5C%20r_%7Bplanet%7D%3D6371%5C%20km%3D6371000%5C%20m%5C%5C%5C%5CArea%5C%20of%5C%20earth%5C%20disk%3D%5Cpi%20%286371000%29%5E2%5C%5C%5C%5Ca%3D1.5%2A10%5E8%5C%20km%3D1.5%2A10%5E%7B11%7D%5C%20m%5C%5C%5C%5CArea%5C%20of%5C%20earth%5C%20orbit%3D4%5Cpi%20a%5E2%3D4%5Cpi%20%281.5%2A10%5E%7B11%7D%29%5E2.%5C%5C%5C%5CTherefore%3A%5C%5C%5C%5C%5Cfrac%7BArea%5C%20of%5C%20earth%5C%20disk%7D%7BArea%5C%20of%5C%20earth%5C%20orbit%7D%3D%5Cfrac%7B%5Cpi%20%286371000%29%5E2%7D%7B4%5Cpi%20%281.5%2A10%5E%7B11%7D%29%5E2%7D%20%20%3D4.5%2A10%5E%7B-10%7D%5C%5C%5C%5C)
This ratio represents the fraction that would be blocked if the planet did not reflect any light, hence:
fraction of the total emitted sunlight reflected by earth = 29% of 4.5 * 10⁻¹⁰ = 0.29 * 4.5 * 10⁻¹⁰ = 1.305 * 10⁻¹⁰
Answer:
If a penny represents one years, 4.54 billion pennies are needed to represent the age of the Earth.
Explanation:
The equivalent number of pennies is the age of the Earth divided by the age of a penny. That is:
![n = \frac{4.54\times 10^{9}\,years}{1\,\frac{year}{penny} }](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7B4.54%5Ctimes%2010%5E%7B9%7D%5C%2Cyears%7D%7B1%5C%2C%5Cfrac%7Byear%7D%7Bpenny%7D%20%7D)
![n = 4.54\times 10^{9}\,pennies](https://tex.z-dn.net/?f=n%20%3D%204.54%5Ctimes%2010%5E%7B9%7D%5C%2Cpennies)
If a penny represents one years, 4.54 billion pennies are needed to represent the age of the Earth.