If an object is propelled upward from a height of 128 feet at an initial velocity of 112 feet per second, then its height h after t seconds is given by the equation h equals negative 16 t squared plus 112 t plus 128. after how many seconds does the object hit the ground? round to the nearest tenth of a second.

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?