7) Mr. Hernandez's science class learned that green plants use sunlight, water, and carbon dioxide to make their own food and release oxygen in the process. How can the class explain how
animals complete the oxygen-carbon cycle?
O Animals take in the oxygen, but do not release gas as they use energy.
O Animals take in carbon dioxide and use it to make food.
O Animals take in oxygen and release nitrogen as waste.
O Animals take in oxygen and as they use energy, carbon dioxide is released as waste.

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?