Question on calculating RMS speed

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SUMMARY

The discussion focuses on calculating the root mean square (RMS) speed of particles in a fluid, specifically using a spherical particle of diameter 3.00 µm in water at 20 degrees Celsius. Participants confirm the use of the equation (3/2)kT = (1/2)mv² to relate kinetic energy to mass and velocity. The conversation also addresses the need to calculate the volume of the particle to determine its mass and subsequently its RMS speed. Additionally, the discussion includes tasks for modeling a 70.0 kg body and finding the diameter of a particle with an RMS speed equal to its diameter divided by 1 second.

PREREQUISITES
  • Understanding of kinetic theory of gases
  • Familiarity with the equation for kinetic energy
  • Knowledge of volume calculations for spherical objects
  • Basic principles of Brownian motion
NEXT STEPS
  • Calculate RMS speed for various particle sizes using the equation (3/2)kT = (1/2)mv²
  • Explore the implications of Brownian motion on particle dynamics in fluids
  • Investigate the relationship between particle mass and RMS speed in different mediums
  • Learn about the applications of RMS speed in real-world scenarios, such as in colloidal systems
USEFUL FOR

Students and professionals in physics, particularly those studying thermodynamics, fluid dynamics, and molecular motion, will benefit from this discussion.

Eiano
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molecular motion is invisible in itself. when a small particle is suspended in a fluid, bombardment by molecules makes the particle jitter about at random.Robert Brown discovered this motion in 1827 while studying plant fertilization. Albert Winstein analyzed it in 1905 and Jean Perrin used it for an early measurement of Avogadro's number. The visible particle's average kinetic energy can be taken as 3/2kbT, the same as that of a molecule in an ideal gas. Consider a spherical particle of density 1000 kg/m^3 in water at 20 degree Celsius.

a)For a particle of diameter 3.00um, evaluate the rms speed.

b) The particle's actual motion is a random walk, but imagine that it moves with constant velocity equal in magnitude to its rms speed. In what time interval would it move by a distance equal to its own diameter?

c)Repeart parts (a) and (b) for a particle of mass 70.0kg, modeling your own body.d) Find the diameter of a particle whose rms speed is equal to its own diameter divided by 1 s.



So far I think that i have to use an equation like m=Pv and 1/2mv^2

(3/2)kT=(1/2)mv^2

anyone care to let me know if I am on the right track?
Thanks!
 
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I think your on the right track for part number 1. Now look you have the diameter of a perfect sphere particle. Find the volume of just 1 particle (using the volume of a sphere) and you should be able to come up with the mass of one particle.

Then you should be able to use your equation.
 

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