An alert physics student stands beside the tracks as a train rolls slowly past. he notes that the frequency of the train whistle is 496 hz when the train is approaching him and 478 hz when the train is receding from him. using these frequencies, he calculates the speed of the train. what value does he find? (assume the speed of sound in air is 343 m/s.)

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is transformed ⇒ as it changes into other forms of energy.

You want to lose weight and have been trying to decide which type of fad diet is best for you. you ask your doctor, who responds that a. fad diets are a temporary fix but generally don't have any side effects b. fad diets can be used several times a year to maintain a healthy weight c. fad diets can be risky for your health and, in the long run, do not work d. fad diets should never be used one right after the other; there should be a break between them select the best answer from the choices provided. a b c d

I’ve been stuck on this for a while