Which best describes longitudinal waves?
a. compressions and rarefactions make up longitudinal waves, which can only travel in matter.
b. light energy travels in longitudinal waves and can travel in either matter or empty space.
c. longitudinal waves carry sound energy and are made up of crests and troughs.

What is the temperature in degrees celsius of a substance with a tempature of 49k

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?

The star nearest to our sun is proxima centauri, at a distance of 4.3 light-years from the sun. how far away, in km, is proxima centauri from the sun?