- #1
rohanlol7
- 67
- 2
Homework Statement
An estimate of the mass of the Coma cluster can be made from the velocity of the galaxies relative to the centre of mass of the cluster; the velocities are around 2000 km s-1. The stars that form the cluster have been together for a long time. Show that a simple model will predict a mass of the cluster of the order of 2*10^43kg. The radius of the Coma cluster is about 10^21m.
Homework Equations
GMm/R^2 =Mv^2/R
The Attempt at a Solution
Tried a few things. First i tried to consider that as a spherical hollow shell. I calculated by using the above equation ( just plugin in values ) and i was off by a factor of 3. Next i tried to consider 2000 as being the AVERAGE speed. This time i was wrong by a factor of about 10.
I tried to model it as a disk but that seemed to complex