The answer is given correctly as a fraction. Chapter 12 8. Remember the difference between floating and submerged objects. Ignore the condensation on the outside of the glass and try this at home. Chapter 13 23.
Air acts just like water.
Remember a volume of gas has weight. Water works like air, but will want to seek its own height, and remember Bernoulli. Remember the plane does not stay at one position in the sky. The question is asking if the boom occurs only at the moment when the speed of sound is exceeded. Chapter 19 13.,24.