Automotive Force on dog's head out of car sunfoof

  • Thread starter Thread starter oneshortplanck
  • Start date Start date
  • Tags Tags
    Car Force Head
AI Thread Summary
The discussion focuses on calculating the wind force acting on a dog's head at 50 mph through a car sunroof, using the drag equation and wall loading calculations. The frontal area of the dog's head is noted as 0.0314 m², with a drag coefficient initially assumed to be 2. Participants identify that the drag coefficient may be too high and emphasize the need for correct unit conversions, specifically converting speed from mph to m/s. The calculations yield similar results, but both methods are deemed incorrect due to unit issues and assumptions about the drag coefficient. Accurate calculations are essential for understanding the forces involved in this scenario.
oneshortplanck
Messages
2
Reaction score
0
(i have made this thread as i previously had it in the aero section and it was probably not getting the attention such an important question deserves.)

lets use the sunroof as an example for simplicity.
what force is the wind acting on the dog at 50mph/22.3m/s?
dog head diameter = 0.2m
therefore frontal area of dog head is 0.0314m^2
Drag coefficient = 2
air density = 1.22

here is my attempt (#1) based on wall loading calculations:
0.00256 * 50 * 50 = 6.4 lb/ sq feet = 306.4Pa

0.0314 * 306.4 * 2=19.25N

here is my attempt (2) based on drag equation
2 x ((1.22 x 50^2)/2) * 0.0314 = 19Nany thoughts
 
Engineering news on Phys.org
Yayyy! They're approximately equal.
 
But both equally wrong unfortunately! You need to use the correct units in the drag equation, mph won't do. Also, 2 for Cd seems high for a dogs head, where did you get that from?
 
The tongue flapping contributes to an anamalous CD value.
 
  • Like
Likes billy_joule
billy_joule said:
But both equally wrong unfortunately! You need to use the correct units in the drag equation, mph won't do. Also, 2 for Cd seems high for a dogs head, where did you get that from?

the first is correct units, but the second should read
2 x ((1.22 x 22.352^2)/2) * 0.0314 = 19N

yes, i agree on the 2 cd, perhaps its the engineering factor of safety.
 
Here's a video by “driving 4 answers” who seems to me to be well versed on the details of Internal Combustion engines. The video does cover something that's a bit shrouded in 'conspiracy theory', and he touches on that, but of course for phys.org, I'm only interested in the actual science involved. He analyzes the claim of achieving 100 mpg with a 427 cubic inch V8 1970 Ford Galaxy in 1977. Only the fuel supply system was modified. I was surprised that he feels the claim could have been...
TL;DR Summary: Heard in the news about using sonar to locate the sub Hello : After the sinking of the ship near the Greek shores , carrying of alot of people , there was another accident that include 5 tourists and a submarine visiting the titanic , which went missing Some technical notes captured my attention, that there us few sonar devices are hearing sounds repeated every 30 seconds , but they are not able to locate the source Is it possible that the sound waves are reflecting from...
Back
Top