'O' Level Physics (Pressure)

• Dixon999

  29 Feb 08, 09:11

  There's this TYS qn (D04/P1/Q15)

  Water of depth 10 m exerts a pressure equal to atmospheric pressure. An air bubble rises to the surface of a lake which is 20 m deep. When the bubble reaches the surface, its volume is 6 cm³. What was the volume of the air bubble at the bottom of the lake?

   

  A 2 cm³  (Ans)          B 3 cm³            C 12 cm³          D 18 cm³

   

  Can somebodi enlighten me (in detail) as to how to find the volume? Wat formula do I use? 

  Domo Arigato Gozimasu

• eagle

  29 Feb 08, 09:36

  i taught this to my ex tuition students before. 2 of them asked the same question.

   

  at surface:
  pressure, P1 = 1atm (atmospheric pressure equivalent to 10m of water), V1 = 6cm³

  at bottom of lake:
  pressure, P2 = 3 atm (atmospheric pressure + 20m of water), V2 = unknown

  Using Bolye's Law, P1V1 = P2V2

  V2 = 2cm³

• Dixon999

  29 Feb 08, 09:52

  Thanx 4 ur prompt reply. I understand liao!

• BaoBei92

  5 Mar 08, 17:05

  Wahhhhhhs. If O'level pop this question out, I'll throw away marks for sure. :<. I don't understand at all.