Four skydivers jump from a helicopter. Assuming that we can neglect air resistance, which diver is falling the fastest and why?

A
Diver A because he has the least mass and so the force of gravity is acting greater on him.
B
Diver D because he has the greatest mass and so the force of gravity is acting greater on him.
C
All divers are falling at the same rate because the force of gravity is the same for each of them.
D
All divers are falling at the same rate because the rate at which an object falls is independent of mass.

Atrain is traveling at 30.0 m/s relative to the ground in still air. the frequency of the note emitted by the train whistle is 262 hz. the speed of sound in air should be taken as 344 m/s. what frequency (f approach) is heard by a passenger on a train moving at a speed of 18.0 m/s relative to the ground in a direction opposite to the first train and approaching it? what frequency (f recede) is heard by a passenger on a train moving at a speed of 18.0 m/s relative to the ground in a direction opposite to the first train and receding from it?