# Doppler Shift/Wien's Law/Hubble Constant Problems

1.) If the actual value of the Hubble Constant is determined to be 72.3517 km/sec/MPC, what would this give for the age of the Universe?
* Could I possibly use V= H*D to find what the age of the universe is.

2.) What would be the Wien's Law predicted wavelength for an accretion disk heated to 300 million Kelvins? What would be the Doppler Shift if this disk was rotating in 75 minutes at a distance of 1 A.U. from the compact core remnant that it is orbiting?
*I used Wien's Law here and got the wavelength to be .0966 angstroms. For the second part of this problem could I use V= H*D to find the doppler shift.

3.) What would be the radial velocity (from the Doppler shift) of a quasar 12 billing light years away using the standard value of the Hubble Constant, 72 km/sec/MPC?
shift(nm) = rest wavelenght (nm) * radial velcity/speed of light this is the equation I presume I might use here.

4.) Assume a power output of 50,000 watts for a radio station at a receiver distance of 50 miles. What would be the power received on the Moon? What would be the power received on Alpha Centauri?
* Can I use the inverse square law here.

5.) Suppose a very distant globular cluster in another galazy is observed to have an apparent diameter of 0.15 arcsec with the Hubble Space Telescope. Assuming it to be an average size globular cluters (50 pc), how far away is it located?
I think I could use this equation to figure out how far away it is d= x/theta.