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Here's where the fun really starts. Taking the data from your test runs, you're going to predict where the marble will land, and then find out if you're right!

You need to measure the height of the chair, or other surface, that your target cup is sitting on. Record this in the T cell on your Data Table. Switch back over to the ProMotion window, and enter the new 'Land Y' as the 'height' of the chair. You also need to decide how far out you want the chair (within reason). Enter that distance into the 'Land X' field. Everything else will stay the same as the last time you ran the applet, so go ahead and click 'New Graph'. Note the computed 'Initial Velocity' on your Data Table, in the V0 slot under 'Design Data' along with the new landing point, X1.

Switching again to DataFlyer, use the blue slider to move the point on the curve till it matches (very closely) the new computed 'Initial Velocity'. As you move the slider, observe the coordinate pair listed on the graph at the point you're moving. The X value is velocity. But, the other half is the launch height!

Once you have the point nearly matching the computed velocity, note the new height in the H slot under 'Design Data' that corresponds to the other two pieces of information already recorded. It is possible that you picked an X1 that is too far out, in which case you will need to repeat the above procedure, moving the 'Land X' closer.

Now you need to verify all your work by launching your marble from the calculated height. Measure up the side of your ramp again, and mark your lauch point with a piece of masking tape. Set your target in the middle of the chair, and place it in a straight line out from the end of the ramp the distance you picked. once you're sure you have everything positioned correctly, go ahead and release your marble.

If you did everything right, your marble just landed in its target. Congratulations, you're on the path to future design!

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