ch11 physics

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Questions and Answers

What causes the upward or buoyant force on a swimmer?

The atmospheric pressure above the swimmer

The pressure difference created by the swimmer's movement

The weight of the swimmer alone

The greater depth of water underneath (correct)

How does air pressure change as altitude increases?

Air pressure fluctuates without a predictable pattern

Air pressure remains unchanged with altitude

Air pressure decreases with increasing altitude (correct)

Air pressure increases significantly at high altitudes

What is the primary reason for the pressure increase when diving underwater?

The atmospheric pressure alone

The buoyancy forces acting on the diver

The increased density of water compared to air (correct)

The movement of the water due to waves

What is the formula for calculating pressure due to the weight of a fluid?

Pressure = Weight / Area Signup and view all the answers

What is the effect of depth on pressure in a fluid?

Pressure increases with depth due to increased weight of fluid above Signup and view all the answers

Why does atmospheric pressure vary at the Earth's surface?

The Earth's rotation and large-scale flow of the atmosphere Signup and view all the answers

Which statement is true regarding pressure in liquids versus gases?

Liquids are nearly incompressible, while gases are quite compressible Signup and view all the answers

If a phonograph needle supports 1.00 g on a circle 0.200 mm radius, what is an expected pressure in N/m²?

25,000 N/m² Signup and view all the answers

What happens if the fluid depths in a U-shaped manometer are not equal?

There will be flow from the deeper side. Signup and view all the answers

What does mercury in a barometer primarily measure?

Atmospheric pressure Signup and view all the answers

What is the relationship between atmospheric pressure and negative gauge pressure?

Atmospheric pressure exceeds negative gauge pressure by an amount $h\rho g$. Signup and view all the answers

Why is a manometer suitable for measuring blood pressure?

It transmits applied pressure undiminished to both the man's artery and the manometer. Signup and view all the answers

What causes the sensation of heaviness when rising from water?

Loss of buoyant force provided by the water. Signup and view all the answers

What is the maximum pressure called in blood pressure measurements?

Systolic pressure Signup and view all the answers

How does atmospheric pressure typically influence the mercury in a barometer?

It causes the mercury height to rise or fall. Signup and view all the answers

What principle explains why some objects float while others sink?

Archimedes' principle of buoyancy. Signup and view all the answers

What happens to an object in a fluid if the buoyant force is greater than the object's weight?

The object will float at the surface. Signup and view all the answers

When is an object suspended in a fluid?

When the buoyant force equals its weight. Signup and view all the answers

According to Archimedes' principle, how is buoyant force determined?

It equals the weight of the fluid displaced. Signup and view all the answers

What determines whether an object will float or sink in a fluid?

The average density of the object relative to the fluid. Signup and view all the answers

If an object is denser than the fluid, what will occur?

The object will sink. Signup and view all the answers

How does the density of a floating object compare to that of the fluid?

It is less than the fluid's density. Signup and view all the answers

What is indicated about the submerged part of a floating object?

It will vary depending on the object's density. Signup and view all the answers

What happens to the buoyant force when an object is removed from the fluid?

It is replaced by the fluid's weight. Signup and view all the answers

What is the fraction submerged if the density of the object is equal to the density of the fluid?

Exactly 1 Signup and view all the answers

Which statement about specific gravity is correct?

It defines an object's tendency to float based on its density relative to the fluid. Signup and view all the answers

When an object floats, what can be inferred about its specific gravity?

It is less than one. Signup and view all the answers

What principle explains that the buoyant force on an object equals the weight of the fluid displaced?

Archimedes' principle Signup and view all the answers

What happens to an object's apparent weight when it is submerged in a fluid?

It decreases. Signup and view all the answers

If an object experiences an apparent mass loss, what does this loss equal?

The mass of the fluid displaced. Signup and view all the answers

What is the relationship between the fraction submerged of a floating object and its specific gravity?

They are equal. Signup and view all the answers

Which factor determines if an object will sink or float in water?

The object's density relative to water. Signup and view all the answers

What does the equation for density ($ ho = \frac{m}{v}$) represent?

The mass per unit volume of a substance Signup and view all the answers

Which of the following statements about fluid pressure is true?

Fluid pressure is exerted perpendicular to surfaces. Signup and view all the answers

If a 240-g rock displaces 89.0 cm³ of water, what is its density?

2.69 g/cm³ Signup and view all the answers

Which of the following reflects the SI unit of pressure?

Newton per square meter Signup and view all the answers

What volume in cubic meters is occupied by 1 troy ounce of pure gold, given its density of 19.32 g/cm³?

0.000327 m³ Signup and view all the answers

How is the concept of shearing forces relevant to fluids?

Fluids cannot withstand shearing forces. Signup and view all the answers

What determines whether an object floats or sinks in a fluid?

The density of the object relative to the fluid Signup and view all the answers

How is pressure defined mathematically?

$P = \frac{F}{A}$ Signup and view all the answers

Study Notes

Density

Density is a measure of mass per unit volume.
The formula for density is: ρ = m/v, where ρ represents density, m represents mass, and v represents volume.
The SI unit for density is kg/m3.
Water has a density of 1 g/cm3 or 103 kg/m3.

Pressure

Pressure is defined as force per unit area perpendicular to the force.
Formula for pressure: P = F/A, where P represents pressure, F represents force, and A represents area.
The SI unit for pressure is the Pascal (Pa), where 1 Pa = 1 N/m2.
Fluids cannot withstand shearing forces.
Pressure inside fluids is exerted perpendicular to all surfaces.

Variation of Pressure with Depth

Pressure increases with depth in a fluid.
This is due to the weight of the fluid above a given point.
The formula for pressure due to the weight of a fluid is P = hρg, where P represents pressure, h represents depth, ρ represents density, and g represents acceleration due to gravity.
This equation holds for liquids that are nearly incompressible.
For gases, which are compressible, the equation can be applied as long as the density changes are small over the considered depth.
Atmospheric pressure is an example of pressure due to the weight of a fluid (air).
There is no theoretical limit to how large gauge pressure can be.

Manometers

Manometers are devices used to measure pressure.
An open-tube manometer has one side open to the atmosphere.
Mercury manometers are often used to measure arterial blood pressure.
A gauge pressure is defined as the difference between the absolute pressure and the atmospheric pressure.

Barometers

Barometers are devices that measure atmospheric pressure.
They contain a nearly pure vacuum above the mercury in the tube.
The height of the mercury column is proportional to the atmospheric pressure.
Changes in atmospheric pressure are reflected in the rising or falling of the mercury column.

Archimedes’ Principle

The buoyant force on an object in a fluid is equal to the weight of the fluid displaced by the object.
This means that an object appears to weigh less when submerged.
This apparent weight loss is equal to the weight of the fluid displaced.
The buoyant force is always present on objects in fluids, regardless of whether they float, sink, or are suspended.

Density and Archimedes’ Principle

The average density of an object determines whether it floats or sinks.
Objects with an average density less than the surrounding fluid will float.
Objects with an average density greater than the surrounding fluid will sink.
The fraction of a floating object submerged is equal to the ratio of its density to the density of the fluid.

Specific Gravity

Specific gravity is the ratio of the density of an object to the density of water at 4oC.
An object with a specific gravity less than one will float.
An object with a specific gravity greater than one will sink.
The fraction of a floating object submerged is equal to its specific gravity.

Apparent Weight Loss

An object submerged in a fluid experiences an apparent weight loss equal to the weight of the volume of fluid displaced.
This is because the buoyant force acts upwards, counteracting the weight of the object.
On balances that measure mass, the object experiences an apparent mass loss equal to the mass of the fluid displaced.

Cohesion and Adhesion

Cohesion is the force of attraction between molecules of the same substance.
Adhesion is the force of attraction between molecules of different substances.
These forces play a role in phenomena like surface tension and capillary action, which influence the behavior of liquids.

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Description

Explore the fundamental concepts of density and pressure in this quiz. Understand how these physical quantities are defined, their formulas, and how pressure varies with depth in fluids. Test your knowledge on the essential principles that govern fluid mechanics.