http://en.wikipedia.org/wiki/Drag_equationCan.i.say? said:I just want a general formula to figure it out.
What do you mean cross sectional area?russ_watters said:120 mph is roughly the speed of the wind for a skydiver, right? So what is the average person's cross sectional area...?
I know I have been clocked at 210 mph fastest and 90 mph approx. slowest. I am not sure of average area of someone skydiving on with their stomach to the wind. But I was more thinking about the lift I get from my hands. Approx. 25 square inchesruss_watters said:120 mph is roughly the speed of the wind for a skydiver, right? So what is the average person's cross sectional area...?
Is there something more simple? Area, wind speed=lbs?A.T. said:
Area & wind speed is all you need there. You can look up the drag coefficient in some tables:Can.i.say? said:Is there something more simple? Area, wind speed=lbs?
And which one of these profiles is his body in a horizontal position?A.T. said:Area & wind speed is all you need there. You can look up the drag coefficient in some tables:
http://en.wikipedia.org/wiki/Drag_coefficient
He didn't ask about his body, but something that is flat and has a surface area of 25 square inches.zoki85 said:And which one of these profiles is his body in a horizontal position?
He wants to know how slow he can fall. In the wiki page you linked to, there's actually listed drag coefficient range for a "man in upright position"A.T. said:He didn't ask about his body, but something that is flat and has a surface area of 25 square inches.
No, he already knows it's 90 mph.zoki85 said:He wants to know how slow he can fall.
At 90 mph, the drag force on each outstretched flat- to -the- wind 25 square inch hand is 0.00256(k)(90)^2(25/144), where k is the shape factor (I'll use k= 1.3), which works out to about a mere 5 pounds of air drag force on each hand. So when falling straight down belly down with hands closed tight to your body versus hands open and extended away from your body, you increase your exposed area from the assumed 10 square feet to perhaps let's say 11 square feet including extended arms , and now your speed instead of being 90 mph is more like 85 mph, or that order of magnitude. As you know, the more surface area of your body you can expose to the wind, the slower will you fall. And you want a large drag factor...'flat out' versus 'curled up' yields a greater drag...Can.i.say? said:I know I have been clocked at 210 mph fastest and 90 mph approx. slowest. I am not sure of average area of someone skydiving on with their stomach to the wind. But I was more thinking about the lift I get from my hands. Approx. 25 square inches
The force of wind on a flat object can be calculated using the formula F = 0.5 x ρ x A x V2, where F is the force in Newtons, ρ is the density of air in kg/m3, A is the surface area of the object in square meters, and V is the wind speed in meters per second.
Calculating the force of wind on a flat object is important for safety reasons, especially in activities like skydiving. It helps determine the maximum wind speed that an object can withstand without causing damage or danger to the people involved.
The force of wind on a flat object is affected by the density of air, surface area of the object, and wind speed. Other factors such as the shape and orientation of the object, as well as air resistance and turbulence, can also play a role in the calculation.
The denser the air, the greater the force of wind on a flat object. This is because denser air has a higher mass per unit volume, resulting in a greater impact on the object. Altitude, temperature, and humidity are all factors that can affect air density.
The force of wind on a flat object cannot be completely eliminated, but it can be reduced by changing the orientation or shape of the object, or by using materials with lower air resistance. However, in extreme wind conditions, it may not be possible to completely eliminate the force of wind on a flat object.