Betty weighs 432 n and she is sitting on a playground swing seat that hangs 0.41 m above the ground. tom pulls the swing back and releases it when the seat is 0.94 m above the ground. the acceleration of gravity is 9.8 m/s 2 . how fast is betty moving when the swing passes through its lowest position? answer in units of m/s.

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?