Wright State University Lake Campus/2018-1/Ping pong air drag

w:Reynolds number @ w:special:permalink/822809548
The Reynolds number is defined as


 * $$\mathrm{Re} = \frac{\rho u L}{\mu} = \frac{u L}{\nu}$$

where:
 * $$\rho$$ is the density of the fluid (SI units: kg/m3)
 * $$u$$ is the velocity of the fluid with respect to the object (m/s)
 * $$L$$ is a characteristic linear dimension (m). For a sphere L=2R is the diameter.
 * $$\mu$$ is the dynamic viscosity (Pa·s or N·s/m2 or kg/m·s)
 * $$\nu$$ is the kinematic viscosity (m2/s).

w:Viscosity @ w:special:permalink/824605819
The viscosity of air depends mostly on the temperature. At 15 °C, the viscosity of air is 1.81x10−5 kg/(m·s) 18.1 μPa·s or 1.81x10−5 Pa·s. The kinematic viscosity at 15 °C is 1.4810x10−5m2/s or 14.8 cSt. At 25 °C, the viscosity is 18.6 μPa·s and the kinematic viscosity 15.7 cSt.

Here, 1 cSt = 1 mm2·s−1 = 10−6 m2·s −1.

w:Drag (physics) @ w:special:permalink/823381084

 * $$F_D\, =\, \tfrac12\, \rho\, v^2\, C_D\, A$$

Original effort circa 2/1/18
From we estimate an acceleration of 7 cm/s/s at a speed of 50 cm/s.

2/8/18 Thursday phy2400 lab
We will attempt to simulate this with Matlab:
 * https://www.youtube.com/watch?v=cMUyv3d1uZo
 * See also met213.tech.purdue.edu ... Ping Pong Ball Drop

I think we did the Reynold's number thing wrong. I get Re=300 here, and that means C =1 here

At sea level and at 15 °C air has a density of approximately 1.225 kg/m3

Ping pong ball: radius = 20mm; mass=2.7g