What kind of motion for a star does not produce a doppler effect? explain?

The answer is; Transverse (sideways) motion (perpendicular to your line of sight to the object)

Doppler shift effect occurs when an object that is emitting light is either moving closer toward the observer or is moving away. These astronomical objects that are moving towards the observer, he or she will view them in blue wavelength of light. Those that are moving away will seem to emit a red wavelength of light. Doppler shift effect is similar to the high pitch wails of an an ambulance coming towards you and then followed by low pitch wails by the same ambulance when it passes past you and is moving away from you.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.