How many miles per hour does it take to break the sound barrier?

The difference between a red shift and a blue shift has to do with wavelength frequency. t or f

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?

Asap and show ! a 14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.