Wright State University Lake Campus/2018-1/Ping pong air drag
The Reynolds number is defined as
- is the w:density of the fluid (SI units: kg/m3)
- is the velocity of the fluid with respect to the object (m/s)
- is a characteristic linear dimension (m). For a sphere L=2R is the diameter.
- is the dynamic viscosity (Pa·s or N·s/m2 or kg/m·s)
- is the kinematic viscosity (m2/s).
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.
Original effort circa 2/1/18
From this graph 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:
Ping pong ball: radius = 20mm; mass=2.7g