Physics Help Forum Calculating "g - force" acting on an Human Body

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Mar 29th 2018, 07:51 AM #1 Junior Member   Join Date: Mar 2018 Posts: 12 Calculating "g - force" acting on an Human Body Dear friends, I want to know the total g-force acting on an Human Body while accelerating. Code: Weight of the Human Body = 70 Kg; Initial Velocity (Vi) = 0; Final Velocity (Vf) = 22.22 m/s; Start Time (ti) = 0 sec; Final Time (tf) = 1 sec; delta V = Vf-Vi = 22.22 m/s - 0 = 22.22 m/s delta t = tf - ti = 1 s - 0 = 1 sec acceleration (a) = delta V/delta t = (22.22 m/s) / (1 s) = 22.22 m/s2 So, acceleration of the Body = 22.22 m/s2 F = m x a F = 70 Kg x 22.22 m/s2 = 1555.4 Kg-m/s2 or 1555.4 N G of Human Body = 70 Kg x 9.81 m/s2 = 686.7 Kg-m/s2 = 686.7 N = 1g So, g force acting on the Body at 22.22 m/s2 = 1555.4 N / 686.7 N = 2.265 g Answer : 2.265g Is this correct method to calculate the "g- force"? Else,share your idea. thanks to you all, pmk Last edited by SpeedEC; Mar 29th 2018 at 08:10 AM.
 Mar 29th 2018, 11:25 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 703 Yes, But... You have ended up at the correct answer, but you have gone down a side road, around the block, and back. Once you have the acceleration of the body at 22.22m/s/s you can go directly to: 22.22 / 9.81 = 2.265 1g=9.81 how many times larger is 22.22? 22.22 = 2.265 * 9.81 All the messing around with the mass and the force is not necessary. If you write out the equations you used: (70*22.2) / (70*9.81) the "70" at the top and bottom of the division cancels SpeedEC likes this. __________________ ~\o/~
 Mar 29th 2018, 12:03 PM #3 Junior Member   Join Date: Mar 2018 Posts: 12 Thank you woody for the reply. Direction of g-force - Horizontal - Chest to Back - Eyeball-in direction; Safety - with proper cushion provided around the human body; Impact Distribution - uniform distribution throughout the body; Acceleration - 22.22 m/s2 Duration = 1 second After 1 second, body acceleration will be 0 and maintain the uniform velocity of 80 KMPH for few seconds, say around 15 seconds. I like to know that can the human body withstand against the 2.265g? thanks, pmk
 Mar 29th 2018, 06:46 PM #4 Senior Member     Join Date: Jun 2016 Location: England Posts: 703 2 to 3g should be fine for a healthy person, no heart conditions in particular! There are fairground rides that reach that level. Fighter Pilots can withstand up to 9g for short periods. The limiting problem is (usually) the heart being unable to pump sufficient blood to the brain. Moving the rib-cage to fill the lungs with oxygen can also become an issue. SpeedEC likes this. __________________ ~\o/~
 Mar 30th 2018, 12:43 PM #5 Junior Member   Join Date: Mar 2018 Posts: 12 Thank you Woody. pmk

 Tags acting, body, calculating, g force, g force, human

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