A sound wave traveling through dry air has a frequency of 15 Hz, a wavelength of 23 m, and a speed of 345 m/s. When the sound wave passes
through a cloud of ammonia gas, its wavelength changes to 28 m, while its
frequency remains the same. What is its new speed? (The equation for the
speed of a wave is v= f xx.)
A. 22 m/s
B. 420 m/s
C. 350 m/s
D. 9,700 m/s

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?