exam2 physics pt. 2

What principle explains why water remains at rest in an inverted test tube submerged in water?

Pascal’s Principle – the pressure at any point in the water is the same, so the pressure inside the tube is equal to the atmospheric pressure outside.

How is pressure at depth in a fluid related to the density and height?

The pressure difference between two points in a fluid is ΔP=ρgh where ρ\rhoρ is the fluid’s density, ggg is acceleration due to gravity, and hhh is the height difference.

What did Torricelli discover, and how did it relate to atmospheric pressure?

Torricelli invented the barometer and discovered that atmospheric pressure can support a column of mercury about 760 mm high, helping to measure atmospheric pressure.

How does the pressure at the bottom of a column of water change as height increases?

The pressure increases by ΔP=ρgh with the pressure at the bottom depending on the fluid’s density and the height of the column.

What is the buoyant force?

The buoyant force is the upward force exerted by a fluid on an object submerged in it. It is equal to the weight of the fluid displaced by the object, according to Archimedes' Principle.

What happens when an object’s density is greater than the fluid’s density?

The object sinks because its weight is greater than the buoyant force from the displaced fluid.

How can the buoyant force determine if an object sinks or floats?

If the object’s density is less than the fluid’s density, it floats; if it’s greater, it sinks; if equal, it remains suspended in the fluid.

What is the maximum height a water column can support?

The maximum height is limited by atmospheric pressure, around 32 feet for water.

According to Torricelli’s experiment with mercury, how is atmospheric pressure measured?

Atmospheric pressure is measured by the height of a mercury column, where 1 atmosphere equals about 760 mm of mercury.

What is the relationship between density and pressure in a fluid?

Pressure in a fluid increases with depth, and the pressure difference between two points is given by ΔP=ρgh

What does Pascal’s Principle state?

Pascal’s Principle states that when a fluid is compressed, it exerts pressure equally in all directions.

How does Bernoulli’s principle apply to fluid flow?

Bernoulli’s principle states that in regions of faster flow, the pressure is lower. This helps explain phenomena like why paper rises when air is blown over it.

What is the flow rate in a pipe and how is it related to speed and cross-sectional area?

The flow rate fff is the product of the velocity vvv and the cross-sectional area A, i.e., f=vA

How does the speed of fluid in a pipe change when the cross-sectional area changes?

According to the continuity equation, if the cross-sectional area decreases, the speed of the fluid increases, and vice versa, assuming no leakage.

What is the relationship between speed and area in connected pipes?

If one pipe has three times the cross-sectional area of another, the speed of the fluid in the larger pipe will be one-third of the speed in the smaller pipe.

What is the effect of viscosity on fluid flow?

Higher viscosity increases friction between layers of the fluid, reducing the speed of the fluid near the walls of the pipe, especially in laminar flow.

What type of flow occurs when a fluid flows smoothly and without eddies?

Laminar flow

What is turbulent flow?

Turbulent flow occurs when the fluid moves chaotically with eddies, whorls, and irregular streamlines, often at higher speeds.

How does Bernoulli’s equation apply to fluid motion and energy conservation?

Bernoulli’s equation states that the total mechanical energy (kinetic + potential + pressure energy) of an incompressible fluid remains constant along a streamline, provided no external work is done.

How do changes in pipe diameter affect fluid speed and pressure?

In a narrower part of the pipe, fluid speed increases, and pressure decreases, as shown by Bernoulli’s equation and the continuity equation.

What happens when fluid flows from a wider to a narrower pipe?

The speed of the fluid increases in the narrower pipe, and according to Bernoulli's principle, the pressure decreases.

How do non-conservative forces affect energy in fluid systems?

Non-conservative forces, such as friction, result in energy loss in the system, affecting the mechanical energy balance.

What happens when two objects are in contact for long enough?

They reach the same temperature, defined as thermal equilibrium.

What does the Zeroth Law of Thermodynamics state?

If two objects are in thermal equilibrium with a third object, they are in thermal equilibrium with each other.

How do thermometers work?

They measure temperature through properties that change with temperature, such as volume, length, or conductivity.

What is the basic idea behind measuring temperature with a liquid thermometer?

The liquid expands in a thin tube when heated, making it easy to observe the temperature change.

What are the Fahrenheit and Celsius scales?

Fahrenheit and Celsius are temperature scales with a conversion formula:
TF=9over5TC+32
and
TC=5over9(TF−32)

How does a gas thermometer measure temperature?

• By sealing gas in a container and measuring the pressure required to keep the gas at a constant volume.

  • High pressure = high temperature

  • Low pressure = low temperature

What is absolute zero?

Absolute zero is the temperature at which all atomic motion stops, and it is 0 Kelvin (K).

What happens at absolute zero, according to the kinetic theory of gases?

Gas particles would stop moving, leading to zero pressure, as temperature and pressure are related.

How does mechanical work affect temperature?

Work can increase an object's temperature, as demonstrated by Joule’s experiment using a falling mass.

Is temperature energy?

No, temperature is a measure of how hot or cold something is, but it is related to energy because energy transfer (heat) can change temperature.

How does heat flow between two objects?

Heat flows from the hotter object to the cooler one, and the temperature of the hot object decreases while the cold object's temperature increases.

What does the first law of thermodynamics state?

The increase in internal energy (ΔU) of a system is equal to the heat added to the system (Q) minus the work done by the system (W).
ΔU=Q−W

What is specific heat capacity?

It is the amount of heat required to raise the temperature of a unit mass of a material by one degree Celsius.

How do different materials respond to heat?

Different materials change temperature by different amounts when the same amount of energy is added. Water, for example, has a specific heat of 4.19 J/g°C

How do you calculate the heat required to change the temperature of a substance?

Use the formula:
Q=m⋅c⋅ΔT
where mmm is mass, ccc is specific heat, and ΔT is the change in temperature

What is latent heat?

• Latent heat is the amount of heat required to change the phase of a substance without changing its temperature.

  • Latent heat of fusion (melting ice): ~80 cal/g

  • Latent heat of vaporization (boiling water): ~550 cal/g

How do you calculate the heat required to melt ice?

Use the formula:
Q=m⋅Lf
where mmm is the mass of ice, and Lf is the latent heat of fusion

What is the energy required to change the temperature and phase of ice?

The total energy required is the sum of the energy to heat the ice to 0°C and the energy to melt the ice into water.

• Example: 1,000 cal to heat ice + 16,000 cal to melt it = 17,000 cal total.

What makes water unique in terms of thermal energy?

Water has high specific heat, a high latent heat of fusion, and a high latent heat of vaporization, meaning it can store and transfer large amounts of heat.

What is the mass difference between the sphere with air inside and without air inside?

The difference in mass is 0.8 grams with an uncertainty of ±0.05 grams

How do you convert mass from grams to kilograms?

To convert mass from grams to kilograms, divide by 1000:

mass=0.8 grams×1.00 kg/1000 grams=0.0008 kg

How do you calculate the volume of the sphere in cubic centimeters?

The volume V of the sphere can be calculated using the formula:

V=4/3πr3

Where r=5.5 cm, so:

V=43π(5.5)3≈696.91 cm3

How do you convert volume from cubic centimeters to cubic meters?

• To convert from cubic centimeters to cubic meters, multiply by (1 m/100 cm)3:

  volume=696.91 cm3×(1.0 m/100 cm)3=0.00069691 m3

How do you calculate the density of air?

The density ρ\rhoρ is calculated as the mass divided by the volume:

ρ=mass/volume=0.0008 kg/0.00069691 m3≈1.14792 kg/m3

What is the accepted value for air density?

The accepted value for air density is approximately 1.2 kg/m3