1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Density question - can a heavy object float in water ?

  1. Mar 1, 2012 #1
    Would a big ball weighing 100kg with a diameter of 1 meter float in water?

    I guess my question is, no matter how heavy an object might be, as long as it is less dense than water, it will float no matter what, right? Like even if that ball were made of a thick layer of steel (a few inches), as long as it is hollow/empty on the inside (and big enough so that its density is lower than water's), it would float, wouldn't it?

  2. jcsd
  3. Mar 1, 2012 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    As long as the object weighs less than the water it would displace if submerged, it will float. So yes, as long as the density of the object, including any hollow areas, is less on average than water it will float.
  4. Mar 1, 2012 #3
    Boats can float and I'm pretty sure they are heavier than 100kg's
  5. Mar 1, 2012 #4
    That's what I thought, thanks for the replies!! (and the link to Wikipedia, Drakkith! It's helpful)
  6. Mar 1, 2012 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Okay, but a cubic meter of water is a thousand kg.

    The key is the density, not the total mass. If you include the air inside the boat then it is less dense than water, therefore it floats.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook