Question

A piece of wood is floating at the surface of some water as illustrated (the diagram is not to scale). The wood has a circular cross section and a height h = 4.0 cm. The density of water is 1.00 g/cm3. The distance y from the surface of the water to the bottom of the wood is 3.0 cm. The density of the wood is (in g/cm3):


Question 1 options:

A)Impossible to determine because the area of the cross section is not given.

B)12

C)0.75

D)0.25

Answer 1

the volume underwater is area*h=area*3
mass of water displced=densitywater*volume
= 1g/cm^3*area*3

This is equal to the weight of the wood:
weight wood=densitywood*volume
= densitywood(area*4cm)

set them equal
1*area*3=densitywood*area*4

density wood=.75g/cm^3