(Solved): Around 66 million years ago, a massive asteroid impact was believed to wipe out all dinosaurs on E ...

Around 66 million years ago, a massive asteroid impact was believed to wipe out all dinosaurs on Earth. Millions of microscopic organisms were killed off. Invertebrates vanished from land and sea. Scientists believe that the dust particles suspended by the impact floated in the sky for a very long time, severely influencing the temperature and photosynthesis on Earth. Use your knowledge of gravitational settling to estimate how long it takes for the particles to settle down. - Assume dust particles were suspended evenly in Earth's troposphere, which has an average height of \( 5 \mathrm{~km} \) - Assume all of the particles have the same size of \( 1 \mu \mathrm{m} \) - Assume the Cunningham correction factor is 1, and particle settling was in the Stokes regime \( (\operatorname{Re}<1) \) a) Assume there is no mixing in Earth's troposphere. How many years does it take so that \( 95 \% \) of the particles settle on the ground? b) Assume Earth's troposphere is well-mixed. How many years does it take so that \( 95 \% \) of the particles settle on the ground?