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Consider an object that floats in water but sinks in oil. When the object floats

ID: 2107030 • Letter: C

Question

Consider an object that floats in water but sinks in oil. When the object floats in water, half of it is submerged. If we slowly pour oil on top of the water so it completely covers the object, the object, moves up. stays in the same place. moves down. Two identical cups are filled to the same level with water. One of the two cups has ice cubes floating in it. When the ice cubes melt, in which cup is the level of the water higher? The cup without ice cubes. The cup with ice cubes. It is the same in both

Explanation / Answer

a) suppose that oil is added and it is in the same position=>buoyant force on the object increases, it moves upward to decrese the total buoyant force and balance it with its weight.

b)suppose the volumes before the ice melts be, v1=v2+v(ice),v1is vol of water in the 1st beaker, v2 vol of water in the second beaker.

now if ice melts to water,v of water formed by melted ice= v(ice)(.92) < v(ice)

so we get v1>v2+v(melted ice) => the cup without ice cubes has water level higher