Penetrative power of electromagnetic waves

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

A100 kg running back runs at 5m/s into a stationary linebacker. it takes 0.5 for the running back to be completely stopped

Astone weighing 1.5 kilograms is resting on a rock at a height of 20 meters above the ground. the stone rolls down 10 meters and comes to rest on a patch of moss. the gravitational potential energy of the stone on the moss is joules.