How Can You Measure the Force of a Punch?

[Jesstilla]

Hello,

I am trying to help a student set up an experiment in which he needs to measure the force of a punch. Any suggestions on what equipment/sensor I can use to do this?

Thanks!
Jessie

 

[berkeman]

Hello,

I am trying to help a student set up an experiment in which he needs to measure the force of a punch. Any suggestions on what equipment/sensor I can use to do this?

Thanks!
Jessie

Welcome to the PF.

One option that comes to mind is a simple spring scale (like you weigh food on) and a video camera. Orient the scale horizontally, and record the dial with the video camera. Then step back through the video frame-by-frame, and plot the readings.

You would need to look around some to find the spring scale that is most suited to punching (short/stiff travel spring, light dial for quick readout, etc.). Or you could make one, as part of the overall project! Make a platform with spring(s), and use some sort of marking scheme to show the displacement. Then use the spring equations to calibrate the whole setup...

 

[eczeno]

this is a complicated problem. first of all, asking 'what is the force?' does not really make sense. the force exerted during a punch will vary greatly. a more appropriate question might be what is the average force exerted during a punch, but even this is probably not what you want because the 'real' effect of the punch will depend on the time of contact. I think a better measure of what a person might think of as the effect of the punch would be the impulse. this is the average force multiplied by the time of contact.

the only way i can think to do this is with a digital force meter that can take many force measurements in a very short time. then you can do a numerical integration to find the impulse.

spring scales and the like are good for measuring constant forces, but will not be very effective for a quickly varying force like that of a punch.

good luck