Sound

Question 1

Does sound travel faster or slower in hot air?

Answer 1

faster

Question 2

Does sound travel faster or slower in Helium (as opposed to air)

Answer 2

faster

Question 3

Energy is conserved and so the total energy on the surface of a wavefront is constant. As the wavefront expands, the energy is more spread out and hence intensity decreases. If the intensity at a distance R is I, what is the intensity of the wave at a distance of 3R? Assume isotropy.

Answer 3

I/9

Question 4

doppler shift

Answer 4

observed change in frequency based on the motion of the source and/or observer