## Projectile motion part 1 Onedimensional motion Physics Khan Academy

Welcome back. I'm not going to do a bunch ofprojectile motion problems, and this is because I thinkyou learn more just seeing someone do it, and thinkingout loud, than all the formulas. I have a strange notion that Imight have done more harm than good by confusing you with a lotof what I did in the last

couple of tutorials, so hopefullyI can undo any damage if I have done any, or even betterhopefully, you did learn from those, and we'lljust add to the learning. Let's start with ageneral problem. Let's say that I'm at the topof a cliff, and I jump instead of throwing something,I just jump off the cliff. We won't worry about my motionfrom side to side, but just assume that I gostraight down.

We could even think that someonejust dropped me off of the top of the cliff. I know these are getting kindof morbid, but let's just assume that nothingbad happens to me. Let's say that at the topof the cliff, my initial velocity velocity initial isgoing to be 0, because I'm stationary before the persondrops me or before I jump. At the bottom of the cliffmy velocity is

100 meters per second. My question is, what is theheight of this cliffé I think this is a good timeto actually introduce the direction notion ofvelocity, to show you this scalar quantity. Let's assume up is positive,and down is negative. My velocity is actually 100meters per second down I

could have assumedthe opposite. The final velocity is 100 metersper second down, and since we're saying that downis negative, and gravity is always pulling you down, we'regoing to say that our acceleration is equal togravity, which is equal to minus 10 meters persecond squared. I just wrote that ahead oftimes, because when we're

dealing with anything ofthrowing or jumping or anything on this planet, wecould just use this constant the actual number is 9.81, butI want to be able to do this without a calculator, so I'lljust stick with minus 10 meters per second squared. It's pulling me down, so that'swhy the minus is there. My question is: I know myinitial velocity, I know my final velocity, right before Ihit the ground or right when I

## PASCO Capstone Tutorial Analysis

Elizabeth: Hello and welcome. I'm Elizabeth. Chong: I'm Chong. E: We're here today to use the PASCO Capstone software, and talk about the feature of tutorial analysis. I've already started an experiment in Capstone, and I have two graph displays and I've imported a movie. The movie's been prerecorded, but Chong'sgoing to explain what the movie's about. C: The movie is going to have a ballisticcart on a PASCO PAStrack,

which is bigger than the one that's shownhere, moving, and a ball shooting up out of it. We're going to track the ball. E: Let's see what the movie looks like. I'llgo ahead and play it here. There it is. C: I notice, Elizabeth, that the movie's veryslow. E: It does appear very slow, almost as ifit were slow motion. Why is thaté

C: That's because the tutorial was shot usinga high speed camera. The other thing I notice is the cart caughtthe ball. E: The cart did catch the ball. That's whywe have this device. This is meant to show the independence ofmotion in the X and Y direction. If we are able to perhaps use our tutorial analysisto show that, that would be a great use for this tool. C: Let's look at how do we go about correctingfor the camera being a high speed camera. E: Great idea. We can actually do that.

We can open up the properties in here, andwe can go into the Movie Playback. C: In this case, the tutorial was filmed in 210frames per second. E: I'll enter 210 here instead of 29. Now let's play that back and see if that looksdifferent. C: That looks more like real life. E: That looks exactly like real life, exactly. C: Perfect. E: Now as Chong said, 210 frames per second.

We're going to end up clicking the mouse on the ball to track it. If we work at 210 frames per second, that's going to be a lot of clicks just to follow that little tiny ball. C: Do we have a tool to address thaté E: We do in fact have a tool. We can addressthat. Let's tell it to advance on each click, let'ssay seven frames. We'll go into the properties and we'll dothe same thing. Actually, before we do that, we need to enterinto tutorial analysis mode. I'll do that.

In tutorial analysis mode now, what I can dois back in the properties in the Overlay menu, I can tell it instead of advancing every oneframe, for it to advance seven. Each mouse click will now be equal to sevenframes. C: Now that we corrected for time, is thereany way that we can correct for distanceé If we wanted our data to be actually usablefor real life. E: That's a great idea. Real world data, yes.We have here a caliper. It's draggable. You'll notice that when Iclick on either end of it, I can drag it. The handy thing is, why don't you tell them aboutthe length of the real track.

### Simi Motion Inverse Dynamics

Hello and welcome to another Simi Motion tutorialtutorial. Today we are going to show you how to createinverse dynamics. With inverse dynamics you can calculate jointangles as well as forces like muscle torques. To create the inverse dynamic, you need movementtutorials with force plate data and a static trial. A static trial is a short tutorial of personstanding in a relaxed state, with all the used markers of the markersetalready applied. To demonstrate the creation of an inversedynamics, we already have such a project with alreadytracked and assigned markers of the lower body.

If you also have come to this point with yourproject, you can start the inverse dynamics. Find Project and select Inverse Dynamics. For the body model, the model for static markerscan be used for full body acquisitions, as well as onlyparts of the body. All body parts which can be calculated withthe available markers will be calculated. For static, select the 3Dcalculation of yourstatic trial. If you do not have it right here in your openproject, you can also import it from another one. Next, select the 3Dcalculation from yourmovement trial for dynamic 3Ddata.

The forces for both legs have to be chosenfrom the force plate data you acquired together with your movement tutorials. For the data to be calculated accordingly,you also need to enter height, weight and sex of the person you tested. It is also important to select the right valuefor the marker size. Now you have also some options to finetunethe results, like interpolation and filtering as well assetting the force threshold for your force data. On the right side of the window you can chooseall the data rows you want to have calculated.

When you have entered everything, click Calculateto finish and close the window. Now you have calculated the inverse dynamics. To test if the data is calculated correctly,you can check with the 3Dview. Via right click and properties you can selectthe XModel and display the calculated inverse dynamicsas skeleton. If the skeleton looks good, the inverse dynamicscalculation was a success. Now you know, how to calculate inverse dynamicsand check if it was correct.