Physics Help Forum Raft - Floating / Density problem

 Nov 21st 2017, 02:58 AM #1 Junior Member   Join Date: Nov 2017 Posts: 4 Raft - Floating / Density problem A raft is 200kg.When raft is empty it float on water by 60% of the volume immersed.John weighs 75kg. Can he sit on the raft without it sinking?How much load can the raft take before it's completely under water? What is the density of the raft?
 Nov 21st 2017, 06:10 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 1,000 How much of the empty raft is below water? This is the amount of water that is displaced by the empty raft. What is the mass (weight) of the displaced water? Hint: this will be the amount needed to balance a 200kg raft. Add John; the mass of the raft + John rises to 275 kg. How much more water will need to be displaced to balance the raft + John? How much lower will the raft have to float to displace this amount of water? If you can answer these questions you should be well on the way to answering the whole problem. I think that you can only determine the density of the raft if you know the density of water. This is a well known standard value (part of the definitions of the standard kilogram and the standard litre). __________________ ~\o/~
 Nov 22nd 2017, 01:15 PM #3 Junior Member   Join Date: Nov 2017 Posts: 4 Thanks.

 Tags density, floating, problem, raft

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post nevermissedabeat Equilibrium and Elasticity 9 Apr 21st 2019 09:55 PM THERMO Spoken Here Thermodynamics and Fluid Mechanics 0 Mar 2nd 2017 04:57 PM ling233 Thermodynamics and Fluid Mechanics 1 Mar 1st 2016 10:19 AM Frostking Electricity and Magnetism 1 Jun 7th 2011 08:07 PM decoy808 Thermodynamics and Fluid Mechanics 1 Nov 23rd 2009 10:58 PM