Pressure
A box standing on a table puts a pressure of 150 Pa on it. What force does the box put on the table if the area of its base is 15 m^2?
2250 N
What is a hydraulic machine?
An device whose operation is based on the laws of equilibrium of liquids in communicating vessels
What quantities does Archimedes' force depend on?
Liquid density, volume of a submerged body, acceleration due to gravity
Lucky question! +10 points
:)
What are communicating vessels? Give real-life examples.
Communicating vessels are vessels that share a common part. Examples: watering can, jug, teapot.
What is the difference between pressure distribution in solids and in liquids/gases?
In solids, pressure is distributed in the direction of application of force, and in liquids/gases, it is distributed evenly in all directions.
Describe the main conclusion of the hydraulic press operation
The gain in force is equal to the ratio of the area of the large piston to the area of the smaller piston.
In what cases will a body swim in a liquid/sink/float on the surface?
Float - Fa > mg, swim - Fa = mg, sink - Fa < mg
Describe the course of Torricelli's experiment. What did it show?
Torricelli sealed one end of a glass tube, filled it with mercury, and inverted it into a bowl. However, not all of the mercury drained. The experiment showed that atmospheric pressure holds the mercury column in place.
How are the heights of liquid columns in communicating vessels related to their density?
Inversely proportional
Why does pressure in liquids and gases increase with depth?
With depth, the weight with which the upper layers press on the lower ones due to gravity increases. This leads to an increase in pressure.
Would the performance of a hydraulic press change if it were moved from Earth to the Moon? Explain the answer.
A hydraulic press will operate identically on Earth and the Moon, as its operation is based on Pascal's law, which is independent of gravity. The piston area ratio remains the same, the fluid flows the same, and the cylinder seals remain the same.
If Archimedes' force acts on all bodies immersed in liquid or gas, why doesn't a person "swim" in air just as he does in water?
Because the Archimedes force depends on the density of the liquid/gas, and the density of air is too low, so Archimedes force in air is not capable of lifting the weight of a person
Describe an aneroid barometer and its structure. What are its advantages over a mercury barometer?
An aneroid barometer is a small, sealed box with a spring. The box is evacuated of air. When the pressure changes, the box changes volume, and the spring moves a hand that displays the pressure. Advantages: safety and compactness.
Describe how a water supply system works. How is it related to communicating vessels?
Water is pumped into a water tower, from where pipes are routed to houses and apartments. Because the tower is higher than the buildings and apartments, the water in the pipes tends to rise, and so when people turn on the tap, it begins to gush forcefully.