General > Climbing NOT (Bitch & moan, Politics)

Velocity of falling objects with differing mass and profile

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sneoh:
Since I was the one who first mentioned terminal velocity, I feel compelled to start a new topic and attempt to set a few things straight.

These are two good sites (be sure to read all of it, not just part of the articles) -
http://www.grc.nasa.gov/WWW/k-12/airplane/termv.html
http://www.ehow.com/list_5761172_ball-drop-science-projects.html

Fact:
Over a short distance of 10 feet, spherical balls of different size, mass, and density will hit the ground at the same time.
If one were to drop a pigeon's feather and a 14lb bowling ball off the Brooklyn Bridge, the bowling ball will hit the water first.

And I believe (going by the equation from the NASA site), a 14lb bowling ball will have a higher terminal velocity than a 1 oz ping-pong ball when dropped from the tallest building in the world.  This is because the equation for terminal velocity V = sqrt (2*mass*G/(Cd*rho*area)) means that V is proportional to sqrt(density*radius of ball) since mass is proportional to density * radius ^3 and area is proportional to radius^2 and Cd for both balls are about the same.
Hence the bowling ball should hit the ground before the ping  pong ball, assuming at least the ping pong ball has reached terminal velocity.

Though I have not practice mechanical engineering the past 15 years, having a Master degree in ME specializing in Fluid Mechanics and Thermodynamics does come in handy at times when I have the discipline NOT to shoot from the hip and say stupid things like a human reaching terminal velocity after 230 feet.  NOT.

Flame on.

danf:
I'm just a hole digger and occasional professional wheelbarrow driver.  My physics understanding and comprehension is limited by what I remember from high school, and with a hot teacher like Ms. Jordan at the front of the class it's amazing that I remember anything that she was actually trying to teach....  No flames from me.  ;D

strandman:
Nice S-- fluid dynamics helps the drinking !  Is F=MA done ?

A long fall generates a lot of force AND hurts- this is my theory and i'm stickin' with it.

strandman:

--- Quote from: danf on May 25, 2013, 09:06:39 pm ---I'm just a hole digger and occasional professional wheelbarrow driver.  My physics understanding and comprehension is limited by what I remember from high school, and with a hot teacher like Ms. Jordan at the front of the class it's amazing that I remember anything that she was actually trying to teach....  No flames from me.  ;D

--- End quote ---

danf- maybe she could have taught you ' fluid dynamics"   8)

danf:
I would have loved to have had a lesson or two! LOL!