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azncuzin202
1st November 2011 - 02:26 AM
A plastic foam (foam = 580 kg/m3) is used to make a life preserver. What volume of foam must be used if it is to keep 29% (by volume) of a 87.8 kg man above the water in a lake? The average density of the man is equal to = 1040 kg/m3.

Can someone show me how to apply the principle? Really stuck on this problem ie. where to begin?
Robittybob1
1st November 2011 - 03:26 AM
QUOTE (azncuzin202+Nov 1 2011, 02:26 AM)
A plastic foam (foam = 580 kg/m3) is used to make a life preserver. What volume of foam must be used if it is to keep 29% (by volume) of a 87.8 kg man above the water in a lake? The average density of the man is equal to = 1040 kg/m3.

Can someone show me how to apply the principle? Really stuck on this problem ie. where to begin?

Start by working out the volume of the man!

Then work out the combined volume of plastic and man so that the combined density is 29% lighter than water with a density of 1kg/l.
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