hw1 - of empty space? 3. How much energy did it take for...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Phys 341: Homework #1 Due Sept. 13 I will give partial credit for partial solutions, but only if you show your work and explain your reasoning. Be careful with units. 1. (a) Consider a globular cluster containing about 10 6 stars in a sphere of radius 10 pc. Use dimensional analysis to estimate the speed with which the stars move inside the cluster. (b) Now repeat the analysis for a galaxy containing 10 11 stars in a radius of 10 kpc. (c) Finally, estimate the speed of galaxies moving in a cluster of galaxies with mass M 10 14 M ± and radius 1 Mpc. 2. The universe is believed to be about 14 billion years old. Use dimensional analysis to estimate the average density of the universe. About how many hydrogen atoms are there in 1 m 3
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: of empty space? 3. How much energy did it take for the Death Star to blow up Alderaan? 1 Lets make an estimate. (a) Use dimensional analysis to estimate the gravitational binding energy of a planet of mass M and radius R . Estimate the gravitational binding energy of Alderaan, assuming it was similar to Earth. (b) How much matter would the Death Star have to convert to energy (by E = mc 2 ) in order to blow up Alderaan? (c) Estimate the size of the room in which the matter was stored. You will need to assume something about the density of the matter; explain your assumptions. Now do you understand why the Death Star was so big? 1 If you dont get the reference, ask around! 1...
View Full Document

Ask a homework question - tutors are online