According to the doppler effect what appears to happen when a light source moves further away from an observer

Afeather of mass 0.001 kg falls from a height of 2 m. under realistic conditions, it experiences air resistance. based on what you know about friction, what can you say about the kinetic energy of the feather as it reaches the ground? acceleration due to gravity is g = 9.8 m/s2. a. ke < 0.0196 j b. ke = 00196 j c. je = 0 j d. ke > 0.0196 j

What’s #16 asking me and how do i solve it?

The force it would take to accelerate an 900-kg car at the rate of 6m/s2