An echo is heard when sound is reflected off a surface. Which of the following best explains this phenomenon?

A. Sound waves strike a barrier and then spread out radially toward an observer.

B. Sound waves travel from one medium to another, bend, and travel back toward an observer.

C. Sound waves bounce off a barrier and then travel back toward an observer.

D. Sound waves are absorbed and reemitted by a barrier. Then, the waves travel back to an observer.

Free runners jump long distances and land on the ground or a wall. how do they apply newton’s second law to lessen the force of impact?

How to calculate voltage drop in a series circuit

Calculate the minimum energy required to remove one proton from the nucleus 126c. this is called the proton-removal energy. (hint: find the difference between the mass of a 126c nucleus and the mass of a proton plus the mass of the nucleus formed when a proton is removed from 126c.) express your answer with the appropriate units. emin e m i n = nothing nothing request answer part b how does the proton-removal energy for 126c compare to the binding energy per nucleon for 126c, calculated using eb=(zmh+nmn−azm)c2?