A girl stands at a distance from a large building. She claps her hands and a short time later hears an echo.
Why is an echo produced when the sound waves hit the building ?

Asap time is ! best answer gets compose at least one well-developed paragraph on the following: define the term concurrent powers, and give an example of a concurrent power of government.

From 0 to 5 seconds john pushed a box 5 meters. from 5 to 10 seconds, paul pushed the same box another 5 meters. who did more work? a. john b. paul c. john and paul did the same amount of work.

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.