What is dark energy?
a. energy inside a black hole
b. a form of the cosmic microwave background radiation
c. electromagnetic radiation that is not in the visible spectrum
d. whatever is causing the accelerating expansion of the universe

Tsunamis are fast-moving waves often generated by underwater earthquakes. in the deep ocean their amplitude is barely noticeable, but upon reaching shore they can rise to an astonishing height of a six-story building. one tsunami generated off the aleutian islands in alaska, had a wavelength of 897km and traveled a distance of 3280km in 4.18h. (a) what was the speed (in m/s) of the wave? find the waves (b) frequency and (c) period.