The speed of a sound wave

is slower than an electromagnetic wave
is faster than an electromagnetic wave
is equal to an electromagnetic wave
cannot be measured

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

What is the role of the ocular lens?

From center station, a train departs every 30 minutes on the fast line and a train departs every 50 minutes on the state line. if two trains depart from center station at 8: 00 a.m., one on each of the two lines, what is the next time that two trains, one on each line, will depart at the same time?