If you suspend a 90-N rock beneath the surface of ethanol, the tension required to support it is only 60 N. What volume of ethanol (density of 789.2kg/cubic meter) must therefore be displaced? Show your work.

Answer 1

When I see show your work, it tells me you are interested in cutting and paste to somewhere else.

So the ethanol is lifting with 30N force, huh? with the density, you can calculate the volume of ethanol that is equal to a weight of 30N.
remember to get density from kg/m^3 to N/m^3, you have to multipy by g (9.8N/kg)