Aroom contains air in which the speed of sound is 343 m/s. the walls of the room are made of concrete, in which the speed of sound is 1 850 m/s.

(a) find the critical angle for total internal reflection of sound at the concrete–air boundary.
(b) in which medium must the sound be traveling in order to undergo total internal reflection?
(c) "a bare concrete wall is a highly efficient mirror for sound." give evidence for or against this statement.

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.