On a day when the speed of sound in air is 340. m/s, a bat emits a shriek whose echo reaches it ...

On a day when the speed of sound in air is 340. m/s, a bat emits a shriek whose echo reaches it later. How far away was the object that reflected back the sound?
 
  What will be an ideal response?

Question 2

Both the microscope and the telescope make the object appear much larger. Why are these two instruments designed differently (e.g., why are the equations for magnification quite different)?
 
  What will be an ideal response?

Question 3

Mercury and the Moon do not have atmospheres because
 
  A) their surfaces are so cold that any atmospheric gases freeze out onto their surfaces
  B) charged particles from the Sun have stripped away their atmospheres
  C) they are rotating too rapidly, causing their atmospheres to be thrown out into space
  D) their gravities are too weak to prevent atmospheric gases escaping into space