## How do you calculate jump height from a force time graph?

### Seth (view profile)

on 16 May 2013

Im looking to write a script that will automatically work out the jump height from force platform data measuring at 1000Hz. The code I have so far is:

```      r = find(truedata==0,1,'first');  % find when first 0 occurs
truedata = (truedata(1:r+1,6)*-1); % cut data      bw = mean(truedata(1:20,1)); % find body weight
Jbw = bw*(r*(1/1000)); % work out impulse caused by body weight      t = [0:1/1000:r/1000]; % change in time
Jall = trapz(t,truedata); % calculate impulse of whole graph      impulse = (Jall-Jbw); % calculate jump impulse
vel = (impulse/(bw/9.81)); % calculate take off velocity
jumpheight = ((vel^2)/(2*9.81)); % equation of motion This however is not giving me the correct answers, could anyone see a problem in my calculations?```

bym

### bym (view profile)

on 16 May 2013

that does not help... look for the {code} button to format your code so that it looks like this:

```r = find(truedata==0,1,'first'); % find when first 0 occurs
truedata = (truedata(1:r+1,6)*-1); % cut data
bw = mean(truedata(1:20,1)); % find body weight
```

and so on...

A short sampling of truedata would be helpful as well

Seth

### Seth (view profile)

on 16 May 2013

``` r = find(truedata==0,1,'first');  % find when first 0 occurs
truedata = (truedata(1:r+1,6)*-1); % cut data
bw = mean(truedata(1:20,1)); % find body weight
Jbw = bw*(r*(1/1000)); % work out impulse caused by body weight
t = [0:1/1000:r/1000]; % change in time
Jall = trapz(t,truedata); % calculate impulse of whole graph         impulse = (Jall-Jbw); % calculate jump impulse
vel = (impulse/(bw/9.81)); % calculate take off velocity
jumpheight = ((vel^2)/(2*9.81)); % equation of motion                     ```
```This however is not giving me the correct answers, could anyone see a problem in my calculations?
```
Walter Roberson

### Walter Roberson (view profile)

on 16 May 2013

The code Seth posted runs lines together. It is not a {code} formatting issue, more newlines are needed to make sense of the code.

## Products

No products are associated with this question.

#### Join the 15-year community celebration.

Play games and win prizes!

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi