Kolokolo Bird Blog Archive Trapped beads, the Stokes law
Today in my collection at the Academy Uczniowska experience exploring the resistance of viscous liquid - Stokes law. Thank you Martin Zarodowi for reminding me of this topic - the experience already done two years ago.
Learning objectives: steam tables calculator Hydrodynamic viscous resistance steam tables calculator (Stokes law), viscosity, laminar and turbulent flow around a Reynolds number, a reference to a number of simple laws and phenomena: fluid displacement (Archimedes' principle), the balance of power, and the principle of dynamics, relationship steam tables calculator speed-road-time , the relation weight-mass-density-volume, steam tables calculator volume of a sphere, transforming and simplifying equations power series, based on inverse square and square, presenting the results in graphs and logarithmic, exponential dependence plotted on a logarithmic scale, linear regression, methods steam tables calculator of measurement, analysis of the biases in the measurements.
Viscosity and Stokes law does not fall within the scope of the curriculum, but the description of the phenomenon (if the law is treated purely phenomenologically Stokes and do not derive it) are so simple that they are perfect for discussion even in the beginning of high school. Experience combines many simple rights and relationships, being an opportunity to stabilize them, reminders and give them sense of usefulness in other branches of physics.
Experience: We measure the speed of polystyrene spheres flowing at a high dish with oil. We set the dependence of the escape of the diameter of the spheres and compared to the relationship resulting from Stokes' law, hence we determine the viscosity of the oil.
Equipment: - high glass cylinder - we had it for about 1m long glass tube with a diameter of 4cm, clogged at the bottom of the stopper and mounted on a tripod laboratory; - Styrofoam balls of different diameters of a few mm - steel wire, a little longer than the cylinder , - stopwatch (on the phone) - micrometer or caliper; - large magnifier; - pliers, tweezers, steam tables calculator - lines, waterproof marker; - a computer program for making diagrams and / or graph paper and log-mm, - a computer program for matching function or a calculator to manually count the regression - Internet (Wiki) or tables of physical constants; - oil or other liquid with a viscosity of the order of 0.1 Pa s (the cheapest cooking oil, the oil may be technical), I (did not check) that very well could see the water and glycerine - changing the proportions can be determined by any viscosity over a wide range, it would be less chance of staining everything around oil stains; - measuring cylinder with a volume of 100-200 cc and weight, - a thermometer handy.
Experience: With a graduated cylinder and weights we determine the density of the oil. Cylinder steam tables calculator fill with oil. Select the marker on the two lines a few inches above the bottom (start) and a few inches below the surface of the (meth), measure the distance between steam tables calculator the two lines. Bend the wire end into a small loop tongs perpendicular to the axis of the wire. A handful of polystyrene beads (used for various technical purposes) to scan through a magnifying glass and choose a few of them, of different sizes from the smallest (about 1 mm) to about 1cm and possibly spherical shape (spheres has a lot of chipping or deformed). We measure the diameters of the spheres steam tables calculator - is the most convenient micrometer, but can be and caliper. Just be careful not to crush the beads during the measurement. Bead is placed on the surface of the oil and a wire loop gently pushes up on the bottom. steam tables calculator This requires a bit of skill - probably several times at the beginning of balls we escape - but it is not very difficult. Jerked releasing bead wire, and the other person measures the time at which it beats flowing steam tables calculator distance marked on our vessel.
Prepare chart data collected: time of departure, depending on the diameter of the spheres. steam tables calculator Calculate the buoyant force which acts on the bead (we know the diameter and density of the oil, for now we can assume that polystyrene is negligible light). This force has to be balanced with the force of law Stokes drag given $ F = 3 \ pi \ eta $ dv, where $ \ eta $ is the coefficient of viscosity, steam tables calculator and $ d $ diameter balls, and $ v $ velocity. Calculate (untangling) the theoretical dependence of the escape time from the diameter of the spheres. $ T \ propto d ^ {-2} $ we compare it with the data collected. We make a graph in log-log scale. Using linear regression, steam tables calculator and / or minimizing the program find the value of $ \ eta $ corresponding to our collected data. We compare it with the value of the array factor for oil viscosity - for glycerol and technical oils find the exact values for vegetable cooking oils viscosity at room temperature is typically between $ \ eta = 80 \ sim 120 \ times 10 ^ {-3} {\ rm kg \ , m ^ {-1} \, s ^ {-1}} $.
Turbulence: We note that the biggest balls (about 1cm) move slightly irregular. The calculated steam tables calculator time for them to deviate from the expected departure. steam tables calculator We discuss the transition between opły
Today in my collection at the Academy Uczniowska experience exploring the resistance of viscous liquid - Stokes law. Thank you Martin Zarodowi for reminding me of this topic - the experience already done two years ago.
Learning objectives: steam tables calculator Hydrodynamic viscous resistance steam tables calculator (Stokes law), viscosity, laminar and turbulent flow around a Reynolds number, a reference to a number of simple laws and phenomena: fluid displacement (Archimedes' principle), the balance of power, and the principle of dynamics, relationship steam tables calculator speed-road-time , the relation weight-mass-density-volume, steam tables calculator volume of a sphere, transforming and simplifying equations power series, based on inverse square and square, presenting the results in graphs and logarithmic, exponential dependence plotted on a logarithmic scale, linear regression, methods steam tables calculator of measurement, analysis of the biases in the measurements.
Viscosity and Stokes law does not fall within the scope of the curriculum, but the description of the phenomenon (if the law is treated purely phenomenologically Stokes and do not derive it) are so simple that they are perfect for discussion even in the beginning of high school. Experience combines many simple rights and relationships, being an opportunity to stabilize them, reminders and give them sense of usefulness in other branches of physics.
Experience: We measure the speed of polystyrene spheres flowing at a high dish with oil. We set the dependence of the escape of the diameter of the spheres and compared to the relationship resulting from Stokes' law, hence we determine the viscosity of the oil.
Equipment: - high glass cylinder - we had it for about 1m long glass tube with a diameter of 4cm, clogged at the bottom of the stopper and mounted on a tripod laboratory; - Styrofoam balls of different diameters of a few mm - steel wire, a little longer than the cylinder , - stopwatch (on the phone) - micrometer or caliper; - large magnifier; - pliers, tweezers, steam tables calculator - lines, waterproof marker; - a computer program for making diagrams and / or graph paper and log-mm, - a computer program for matching function or a calculator to manually count the regression - Internet (Wiki) or tables of physical constants; - oil or other liquid with a viscosity of the order of 0.1 Pa s (the cheapest cooking oil, the oil may be technical), I (did not check) that very well could see the water and glycerine - changing the proportions can be determined by any viscosity over a wide range, it would be less chance of staining everything around oil stains; - measuring cylinder with a volume of 100-200 cc and weight, - a thermometer handy.
Experience: With a graduated cylinder and weights we determine the density of the oil. Cylinder steam tables calculator fill with oil. Select the marker on the two lines a few inches above the bottom (start) and a few inches below the surface of the (meth), measure the distance between steam tables calculator the two lines. Bend the wire end into a small loop tongs perpendicular to the axis of the wire. A handful of polystyrene beads (used for various technical purposes) to scan through a magnifying glass and choose a few of them, of different sizes from the smallest (about 1 mm) to about 1cm and possibly spherical shape (spheres has a lot of chipping or deformed). We measure the diameters of the spheres steam tables calculator - is the most convenient micrometer, but can be and caliper. Just be careful not to crush the beads during the measurement. Bead is placed on the surface of the oil and a wire loop gently pushes up on the bottom. steam tables calculator This requires a bit of skill - probably several times at the beginning of balls we escape - but it is not very difficult. Jerked releasing bead wire, and the other person measures the time at which it beats flowing steam tables calculator distance marked on our vessel.
Prepare chart data collected: time of departure, depending on the diameter of the spheres. steam tables calculator Calculate the buoyant force which acts on the bead (we know the diameter and density of the oil, for now we can assume that polystyrene is negligible light). This force has to be balanced with the force of law Stokes drag given $ F = 3 \ pi \ eta $ dv, where $ \ eta $ is the coefficient of viscosity, steam tables calculator and $ d $ diameter balls, and $ v $ velocity. Calculate (untangling) the theoretical dependence of the escape time from the diameter of the spheres. $ T \ propto d ^ {-2} $ we compare it with the data collected. We make a graph in log-log scale. Using linear regression, steam tables calculator and / or minimizing the program find the value of $ \ eta $ corresponding to our collected data. We compare it with the value of the array factor for oil viscosity - for glycerol and technical oils find the exact values for vegetable cooking oils viscosity at room temperature is typically between $ \ eta = 80 \ sim 120 \ times 10 ^ {-3} {\ rm kg \ , m ^ {-1} \, s ^ {-1}} $.
Turbulence: We note that the biggest balls (about 1cm) move slightly irregular. The calculated steam tables calculator time for them to deviate from the expected departure. steam tables calculator We discuss the transition between opły
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