Mass movement often called mass wasting is the downslope movement of a mass of surface materials such as soil rock or mud. This mass movement typically occurs along hillsides and mountains due to the influence of gravity and can happen very slowly or very quickly. What is mass wasting and why does it occur?
What is the mass flow rate?
Mass flow rate. In physics and engineering, mass flow rate is the mass of a substance which passes per unit of time. Its unit is kilogram per second in SI units, and slug per second or pound per second in US customary units. The common symbol is ( ṁ, pronounced "m-dot"), although sometimes μ ( Greek lowercase mu)...
What is the difference between mass flow and volumetric flow?
Measurements of mass flow are preferred over measurements of volumetric flow in process applications where mass balance (monitoring the rates of mass entry and exit for a process) is important.
How does mass affect the flow rate of a fluid?
For a fluid (a liquid or a gas) the density, volume, and shape of the object can all change within the domain with time and mass can move through the domain. The conservation of mass (continuity) tells us that the mass flow rate mdot through a tube is a constant and equal to the product of the density r, velocity V, and flow area A : Eq #1:
How can we increase the mass flow rate indefinitely?
mdot = r * V * A. Considering the mass flow rate equation, it appears that for a given area and a fixed density, we could increase the mass flow rate indefinitely by simply increasing the velocity.
How to find mass flow rate in kilograms per second?
What is the relationship between volume and mass?
Which is preferred over measurements of volumetric flow?
When we combine proportionality with a specific set of data experimentally gathered from a particular flow element, we?
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Where is the mass flow?
The mass flow rate is the mass of a liquid substance passing per unit time. In other words, the mass flow rate is defined as the rate of movement of liquid pass through a unit area. The mass flow is directly dependent on the density, velocity of the liquid, and area of cross-section.
Where does mass flow occur in plants?
the phloemThe narrowness of the tubes and the existence of plates help to produce pressure differences between different areas of the phloem and to stimulate a vast movement of materials from one place to another. This is known as mass flow. The sucrose produced in the leaf cells is actively transported into the phloem cells.
Does mass flow occur in xylem?
Mass transport in plants takes place in the xylem, which carries water and inorganic ions, and phloem, which carries sugars and amino acids. Water in the xylem moves in one direction and is driven by the transpiration stream.
What is the process of mass flow?
Mass flow is the movement of dissolved nutrients into a plant as the plant absorbs water for transpiration. The process is responsible for most transport of nitrate, sulfate, calcium and magnesium. Diffusion is the movement of nutrients to the root surface in response to a concentration gradient.
What is mass flow in biology?
Mass flow, also known as “mass transfer” and “bulk flow”, is the movement of fluids down a pressure or temperature gradient, particularly in the life sciences. As such, mass flow is a subject of study in both fluid dynamics and biology.
What is mass flow in plants in a level biology?
The mass flow hypothesis is a theory which attempts to explain how solutes are transported from source cells into sinks through the phloem.
What is the process of xylem and phloem?
Xylem transports water and mineral salts from the roots up to other parts of the plant, while phloem transports sucrose and amino acids between the leaves and other parts of the plant....Xylem and phloem.TissueWhat is movedProcessXylemWater and mineralsTranspiration streamPhloemSucrose and amino acidsTranslocation
How does mass flow of the phloem sap occur?
Movement of phloem sap occurs by bulk flow (mass flow) from sugar sources to sugar sinks. The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward).
Is mass flow active or passive?
Bulk flow is the type of transport in bulk and transports large substances like lipids and food particles. It is an energy-consuming transport. Hence, bulk flow is a means of active transport.
What is soil mass flow?
Mass Flow: Nutrient movement to the roots via water is called mass flow. As the corn plant transpires water, it draws water from throughout the soil profile up through the root system. Mass flow accounts for nutrient uptake of mobile nutrients, such as nitrogen and sulfur.
What is mass flow of gas?
Mass flow devices are commonly used for applications requiring high accuracy, precision measurement and control of specific amounts of gas. Imagine you need to flow argon through a mass flow controller at exactly 5 SLPM. When you begin flowing, the temperature and pressure of the gas are 23°C and 20 PSIA.
What is mass flow in animal?
Mass flow transport requires the movement of fluids under a pressure gradient. Larger animals have circulatory systems where the heart generates the pressure gradient necessary for mass flow transport. Water in blood is the liquid involved in the mass flow transport in animals.
What is mass flow in soil?
Mass Flow: Nutrient movement to the roots via water is called mass flow. As the corn plant transpires water, it draws water from throughout the soil profile up through the root system. Mass flow accounts for nutrient uptake of mobile nutrients, such as nitrogen and sulfur.
Which of the following moves mainly by mass flow or bulk flow in a plant body?
Water, minerals and food are generally moved by mass flow.
Why do plants need mass transport?
Plants need to take up water, minerals and carbon dioxide, and transport them to the leaves for photosynthesis . They then move the products of photosynthesis to where they're needed in the plant.
Why is mass transport in plants important?
Mass transport in plants Maintain the diffusion gradients at exchange sites and between cells and their fluid surroundings.
How does compressibility affect mass flow?
We can increase the mass flow through a tube by increasing the area, increasing the total pressure, or decreasing the total temperature. But the effect of increasing velocity (Mach number) is a little harder to figure out. If we were to fix the area, total pressure and temperature, and graph the variation of mass flow rate with Mach number, we would find that a limiting maximum value occurs at Mach number equal to one. There is a technique in calculus to find the maximum (or minimum) value of a function by taking the derivative of the function and setting the resulting equation to zero. Let us apply this technique to the mass flow rate equation. To simplify the exercise, let us define:
What is the mass of an object?
The mass of any object is simply the volume that the object occupies times the density of the object. For a fluid (a liquid or a gas) the density, volume, and shape of the object can all change within the domain with time and mass can move through the domain. The conservation of mass (continuity) tells us that the mass flow rate mdot ...
What is conservation of mass?
The conservation of mass specifies that the mass flow rate through a nozzle is a constant. If no heat is added, and there are no pressure losses in the nozzle, the total pressure and temperature are also constant.
Why does density not remain fixed?
In real fluids, however, the density does not remain fixed as the velocity increases because of compressibility effects . We have to account for the change in density to determine the mass flow rate at higher velocities. If we start with the mass flow rate equation given above and use the isentropic flow relations and the equation of state , ...
What is the mass flow rate?
In elementary classical mechanics, mass flow rate is encountered when dealing with objects of variable mass, such as a rocket ejecting spent fuel. Often, descriptions of such objects erroneously invoke Newton's second law F =d ( mv )/d t by treating both the mass m and the velocity v as time-dependent and then applying the derivative product rule. A correct description of such an object requires the application of Newton's second law to the entire, constant-mass system consisting of both the object and its ejected mass.
What is change in mass?
The change in mass is the amount that flows after crossing the boundary for some time duration, not the initial amount of mass at the boundary minus the final amount at the boundary, since the change in mass flowing through the area would be zero for steady flow .
How to calculate volume flow rate?
The volume flow rate is calculated by multiplying the flow velocity of the mass elements, v, by the cross-sectional vector area, A.
How to increase mass flow rate?
Considering the mass flow rate equation, it appears that for a given area and a fixed density, we could increase the mass flow rate indefinitely by simply increasing the velocity. In real fluids, however, the density does not remain fixed as the velocity increases because of compressibility effects . We have to account for the change in density to determine the mass flow rate at higher velocities. If we start with the mass flow rate equation given above and use the isentropic flow relations and the equation of state , we can derive a compressible form of the mass flow rate equation.
How does compressibility affect mass flow?
The compressibility effects on mass flow rate have some unexpected results. We can increase the mass flow through a tube by increasing the area, increasing the total pressure, or decreasing the total temperature. But the effect of increasing velocity (Mach number) is a little harder to figure out. If we were to fix the area, total pressure and temperature, and graph the variation of mass flow rate with Mach number, we would find that a limiting maximum value occurs at Mach number equal to one. You can generate the numbers to put in the graph by using the calculator. Notice that if you only change the value of the Mach number, the largest mass flow rate occurs for Mach = 1.0. There is a mathematical proof of this result that uses a technique taught in calculus. To find the maximum (or minimum) value of a function, determine when the derivative of the function is equal to zero. Let us apply this technique to the mass flow rate equation. To simplify the exercise, let us define:
What is the maximum airflow limit?
There is a maximum airflow limit that occurs when the Mach number is equal to one . The limiting of the mass flow rate is called choking of the flow. If we substitute M = 1 into Eq #10 we can determine the value of the choked mass flow rate:
What is conservation of mass?
The conservation of mass specifies that the mass flow rate through a nozzle is a constant. If no heat is added, and there are no pressure losses in the nozzle, the total pressure and temperature are also constant.
What is the mass of an object?
The mass of any object is simply the volume that the object occupies times the density of the object. For a fluid (a liquid or a gas) the density, volume, and shape of the object can all change within the domain with time and mass can move through the domain. The conservation of mass (continuity) tells us that the mass flow rate mdot ...
Is the mass flow equation a mess?
The mass flow equation is quite "messy", so here is a JavaScript calculator that solves the mass flow equation for you for both the mass flow rate and the weight flow rate:
What is the difference between bulk flow and diffusion?
The key difference between bulk flow and diffusion is that bulk flow is the movement of a fluid or a mass due to a pressure gradient while diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration along the concentration gradient.
Why is bulk flow important in plants?
Bulk flow is an important process in plants. Water and solutes move along the tracheid and vessels elements of xylem and sieve tube elements of phloem due to bulk flow. Therefore, efficient long-distance transport of liquids in plants takes place with the help of bulk flow.
What is Diffusion?
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration. It occurs along the concentration gradient. Hence, it is a passive process which occurs without the use of energy. It happens on its own. It does not require stirring, shaking or wafting. Liquids and gasses move via diffusion. There are two types of diffusion. They are simple diffusion and facilitated diffusion. Simple diffusion takes place without the help of transporter proteins, while facilitated diffusion takes place with the help of carrier molecules. There are several factors affecting diffusion. They are temperature, size of the particle, steepness of the concentration gradient and area of interaction.
What is the movement of molecules down the concentration gradient?
Diffusion is the movement of molecules down the concentration gradient. Both processes take place during human breathing. Diffusion and bulk flow are also ways of exchanging materials between blood and interstitial fluid. Moreover, both processes are very important in living things, especially in plants.
What type of diffusion does a gas need to move?
It does not require stirring, shaking or wafting. Liquids and gasses move via diffusion. There are two types of diffusion. They are simple diffusion and facilitated diffusion. Simple diffusion takes place without the help of transporter proteins, while facilitated diffusion takes place with the help of carrier molecules.
Which two mechanisms facilitate capillary exchange?
Bulk flow and diffusion are two of three mechanisms that facilitate capillary exchange.
How does diffusion work in living cells?
Here, particles move randomly from place to place. In living cells, diffusion is an important process. Things go in and out from the cells via diffusion . Gas exchange in the alveoli also occurs via diffusion.
Where do Earthflows start?
Earthflows usually begin in a large basin on the upper part of a slope where debris and weathered material accumulate; the movement, usually set off by heavy rainfall, may be relatively slow or very fast, depending on the amount of water present, the angle….
Where do mudflows occur?
Mudflows occur on steep slopes where vegetation is not sufficient to prevent rapid erosion but can occur on gentle slopes if other conditions are met. Other factors are heavy precipitation in short periods and an easily erodible source material.
What is mudflow in water?
Mudflow, flow of water that contains large amounts of suspended particles and silt. It has a higher density and viscosity than a streamflow and can deposit only the coarsest part of its load; this causes irreversible sediment entrainment. Its high viscosity will not allow it to flow as far as a water flow. Mudflow on the Tungurahua volcano, Ecuador.
How fast can mudflows go?
They may rush down a mountainside at speeds as great as 100 km (60 miles) per hour and can cause great damage to life and property. Boulders as large as houses have been moved by mudflows.
How high are mudflow boulders?
They have abrupt and well-defined edges, irregular surfaces, and a lobate appearance; they may be 3 to 6 m (10 to 20 feet) high.
How to find mass flow rate in kilograms per second?
A mass flow rate in kilograms per second will be obtained by multiplying a mass density in kilograms per cubic meter by a volumetric flow rate in cubic meters per second:
What is the relationship between volume and mass?
If we wish to calculate mass flow instead of volumetric flow, the equation does not change much. The relationship between volume (V ) and mass (m) for a sample of fluid is its mass density (ρ):
Which is preferred over measurements of volumetric flow?
Measurements of mass flow are preferred over measurements of volumetric flow in process applications where mass balance (monitoring the rates of mass entry and exit for a process) is important.
When we combine proportionality with a specific set of data experimentally gathered from a particular flow element, we?
Once we combine that proportionality with a specific set of data experimentally gathered from a particular flow element, we have a true equation properly relating all the variables together in our chosen units of measurement.
Overview
In physics and engineering, mass flow rate is the mass of a substance which passes per unit of time. Its unit is kilogram per second in SI units, and slug per second or pound per second in US customary units. The common symbol is (ṁ, pronounced "m-dot"), although sometimes μ (Greek lowercase mu) is used.
Sometimes, mass flow rate is termed mass flux or mass current, see for example Schaum's Outli…
Alternative equations
Mass flow rate can also be calculated by:
where:
• or Q = Volume flow rate,
• ρ = mass density of the fluid,
• v = Flow velocity of the mass elements,
Usage
In the elementary form of the continuity equation for mass, in hydrodynamics:
In elementary classical mechanics, mass flow rate is encountered when dealing with objects of variable mass, such as a rocket ejecting spent fuel. Often, descriptions of such objects erroneously invoke Newton's second law F =d(mv)/dt by treating both the mass m and the velocity v as time-dependent and then applying the derivative product rule. A correct description of such …
Analogous quantities
In hydrodynamics, mass flow rate is the rate of flow of mass. In electricity, the rate of flow of charge is electric current.
See also
• Continuity equation
• Fluid dynamics
• Mass flow controller
• Mass flow meter
• Mass flux