Describe the chemical makeup of most stars?

Which of the following is an example of units for speed

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

Rank the automobiles based on the magnitude of the force needed to stop them, from largest to smallest.2000 kg car going 5m/s500 kg car going 20 m/s1000 kg car going20m/s500 kg car going10m/s1000 kg car going10/s4000 kg car going 5m/s 0 0 603