EPS 200 Density and Pressure Review Questions
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Name: ___________________________
What causes the air pressure that is affecting us right now?
How can you show that air has…
a. Mass?
b. Weight?
What happens to your ear drum when you travel to a higher altitude? (be specific) Why?
Approximate the average air pressure at sea level.
What is the density of water, in g/mL, kg/m3, and kg/L?
How many liters fit in a volume of 1m3?
Approximately how many liters are there in one gallon?
Air pressure pushes against the surface of an average adult human with a total force of about 40,000
pounds. Give two reasons why that force does not crush us.
For each of the following units, tell what property (e.g. volume, mass…) the unit describes.
kg
psi
mL
L
lb
g/cm3 m3
kg/m3 lb/in2 g
cm
Use a diagram, arrows, and words to explain why a suction cup sticks to glass.
Buoyancy is a force that is experienced by any object contained within one or more fluids. Clearly explain
how the force of buoyancy is generated.
State Archimedes’ Principle.
Problems
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What is the formula for density?
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What is the formula for pressure?
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The mass of a box is 2kg, and its sides measure 0.2m, 0.2m, and 5m.
a. What is its volume?
b. What is its density?
A person has a volume of 70L and a density of 0.9kg/L. What is her mass?
A boat has a density of 0.6kg/m3 and a mass of 100kg. What is its volume?
A 140 pound person stands on one foot. The area of the bottom of his shoe is 36in2. If the person’s
weight is distributed evenly across his foot, what pressure is he applying to the ground?
An air compressor produces a pressure of 120psi. Compressed air from the compressor pushes against an
area of 4in2, causing a piston to be propelled forward. What force does the compressed air exert on the
piston?
Cheryl is walking on thin ice. She weighs 100 pounds. The maximum pressure the ice can support is
0.5psi. In order to keep her applied pressure this low, she needs to make sure that she distributes her
weight over a large enough surface area. How much surface area is necessary to keep her from
overloading the ice?
Hint: Use Archimedes’ Principle to solve this problem.