Imagine that we have a small boat floating in our bathtub. We measure the level of water. Now, we place a lead orb on board (so that it does not sink) and measure the level of water again. Now, we take this sphere and put it in water - and measure again.
The level of water will be the highest if the sphere rests on the boat - because when it sinks, its mass will not matter - only volume, and lead is denser than water.

Now, imagine that we do the same experiment wtih styrofoam instead. Is it possible to predict in which scenario more water will be displaced? When the Styrofoam is in boat or in water?

  • 1
    $\begingroup$ Do you mean predict if the Styrofoam displaces more on the boat compared to in the water, or do you mean displaces more compared to lead. Also, what are your thoughts on this? $\endgroup$
    – JMac
    Apr 24 '17 at 10:08

Go by weight. On a scale, weigh the boat, in grams, with the lead. Each gram corresponds to one cubic centimeter of water. Putting the boat in the bathtub will make the water rise by the same amount as if you put in that number of ccs of water.

Repeat for the styrofoam. Fewer grams = fewer ccs = less water rise.

But in either case, if the weight falls out of the boat...

In the lead case the additional ccs are only the weight of the boat itself plus the volume of the lead, so less water rise.

In the styrofoam case, if you allow the styrofoam to float, it will be the same as if it stayed in the boat. If you pull the styrofoam to the botton (by a fine thread), it will be the same as the case of the lead weight falling out.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.