Physics of Fluids Challenge : Will You Sink or Swim?

If an object sinks in a fluid, _____.

• the density of the fluid is greater than the density of the object
• the density of the fluid is less than the density of the object
• the density of the fluid is equal to the density of the object
• density has nothing to do with whether an object sinks or floats, only which state of matter the object is

The pressure you feel under water increases as your depth increases.

• True

• False

When pressure is applied to a confined fluid, the increase in pressure is transmitted equally to all parts of the fluid. This fact is called________.

• Pascal's Principle
• Newton's Principle
• Archimedes' Principle
• Bernoulli's Principle

Archimedes' Principle states that... 

• The buoyant force acting on an object equals the volume of the fluid displaced by the object. 
• The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object.
• The buoyant force acting on an object will always be equal. 

Which direction does buoyant force always push?

• downward
• upward
• all directions
• sponge bob

For incompressible fluids, density changes little with changes in what?

• depth
• temperature
• pressure
• free-fall acceleration

An object exerts 360 N of force on a surface that has an area of 8.0m². How much pressure does the object exert?

• 5.625 Pa

• 45 Pa

• 70 Pa

• 45 N

A simple U-tube or manometer has a side filled with water and another with an unknown blue fluid. Which fluid has the greater density?

• water

• unknown fluid

• both have the same density

A rock of irregular shape sinks to the bottom of water when placed in it. Which two of the following, when used together, could be used to determine its density?

• Measure the mass of the rock on a scale

• Measure the mass of the beaker of water on a scale

• Place the rock in a beaker and measure the change in height of the water

• Place the rock in a beaker and measure the height of the water above it

Assume both sides of the manometer at the right are open to the outside atmosphere, and that the system has had time to reach equilibrium. Rank the fluids in order from most dense to least dense.

• Fluid A, oil, water, mercury

• oil, water, Fluid A, mercury

• mercury, oil, water, Fluid A

• mercury, Fluid A, water, oil