AP Physics 2 : Fluid Statics

Study concepts, example questions & explanations for AP Physics 2

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Example Questions

Example Question #4 : Archimedes' Principle

A ball of mass \(\displaystyle 4kg\) is lightly dropped into a tub with a base of \(\displaystyle 1m^2\). After it sinks to the bottom, the water rises by \(\displaystyle 2.5mm\). Determine the density of the ball.

Possible Answers:

\(\displaystyle .40\frac{kg}{L}\)

\(\displaystyle 1.6\frac{kg}{L}\)

\(\displaystyle .25\frac{kg}{L}\)

\(\displaystyle 4.4\frac{kg}{L}\)

None of these

Correct answer:

\(\displaystyle 1.6\frac{kg}{L}\)

Explanation:

The volume displaced will equal the volume of the ball.

\(\displaystyle V=B*h\)

\(\displaystyle V=1*.0025\)

\(\displaystyle V=.0025m^3\)

\(\displaystyle \rho=\frac{m}{V}\)

\(\displaystyle \rho=\frac{4 kg}{.0025m^3}\)

\(\displaystyle \rho=\frac{1600kg}{m^3}\)

\(\displaystyle \frac{1600kg}{m^3}*\frac{1m^3}{100^3cm^2}*\frac{1000cm^3}{1L}=1.6\frac{kg}{L}\)

Example Question #71 : Fluid Statics

How much of an iceberg is submerged below the water if the density of ice is \(\displaystyle 917 \frac{\textup{kg}}{\textup{m}^3}\) and the density of water is \(\displaystyle 1000 \frac{\textup{kg}}{\textup{m}^3}\)?

Possible Answers:

Cannot be determined without knowing the mass of the iceberg.

\(\displaystyle 91.7 \%\)

\(\displaystyle 8.3\%\)

\(\displaystyle 9.3\%\)

\(\displaystyle 109\%\)

Correct answer:

\(\displaystyle 91.7 \%\)

Explanation:

The volume of the submerged mass is the volume of the mass proportional to the density of the solid to the density of the fluid.

\(\displaystyle V_{sub}= V_{solid}(\frac{\rho_{solid}}{\rho_{fluid}})\)

Determine the amount of ice that is submerged.

\(\displaystyle \frac{V_{sub}}{V_{solid}}= \frac{\rho_{solid}}{\rho_{fluid}}= \frac{917}{1000} = 91.7 \%\)

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