I’ve tried understanding about body movements by reading some of the various white papers and other data, but is way beyond my understanding. I’m not really involved in the mechanics of movement or the forces it generates.
I have a rather simple problem whereby I need to figure the velocity a crouching human, jumping a distance of approximately 60-inches horizontally. I am in the process of designing a potentially, new ASTM standard for Correctional Facilities. We have to design a test whereby, in worst case scenario within a prison cell, a pair of 220-lb. inmates would jump simultaneously off of the only likely piece of prison furniture (steel desk) onto a cantilevered steel bunk (subject of the study). My checking into a potential calculation for this act is as follows, but may not be applicable, as the following formula is used for calculating the range of a standard ‘projectile’ (i.e. bullet, etc.): d = v squared / g X sin2 theta
d = range; v squared = velocity; g = gravitational constant of 32 ft/s squared; theta = launch angle.
Using the formula, I literally had to guess on the velocity a human might produce, which I guessed at 3 ft/s. However, I come up with an unreasonable range of a fraction of a foot (i.e. about 2-3-inches in range). I also tried to work the formula in reverse, whereby I inserted 5-feet for the range, to come up with an estimated velocity. This came out to be approximately 13.6 ft/s! That didn’t seem correct either.
Is there a sort of rule of thumb or range of velocities that may be generated by an average human being, male or female (excluding superhumans)? I just need a reasonable velocity to use in the equation, so that we can set up the test standard. I can provide a drawing indicating the cross-sectional and plan view distances, etc. if someone requires it. I’m not sure if I would be able to attach a .pdf drawing here and have it be readible, but I’ll try. I can work with you on that to email it separately if it doesn’t work out.
Your help and guidance is sincerely appreciated!
Thank you,
Sincerely,
Scott Sanders
(first time user)
Hello Scott,
I can’t give you an exact value for this velocity. But you can consider that a human walks at an average of 4.5 Km/h, so 1.25 m/s. And some one jumping while running (so with non-zero initial velocity) could have a velocity between 8 and 9 m/s.
So for a jump with zero inital velocity you could estimate the speed between 4 or 5 m/s. And that correspond to the 13.6 ft/s you calculated. So i think in the end this is a quite correct value.
Best regards, Sylvain.
Sylvain,
I finally used the information that you had corroborated (ie. on the potential launch velocity for a crouching person performing a jump). Using a standard projectile formula for realistic range results, which takes into account the vertical difference in height between the initial position and the final position, I came up with a potential range of 6.28 feet. My study for a person in a prison cell, using a steel desk to launch from, only had to jump a distance of 5 feet, using a 30-degree angle. The figures seem to make sense, that an average person could jump that far with 13.6 feet/sec initial velocity.
Thank you for your help!
Scott:)