Downhill Lab with iPad Hey, it's not rocket science (or maybe it is... sort of), but all we wanted to do was to determine the effect of changing mass and changing slope on the motion of a cart rolling down a hill. Yes, we can do this effectively with a protractor, stopwatch and pad. But this was much more fun. We used the level on the Multi Measures HD app to determine the slope of the hill. Then we used the iLab timer app to time the trip of the cart to the bottom of the 8 ft. ramp. Finally, we plugged our data into the Numbers app so that we could graph our results. Did we get better results? I doubt it, but we were clearly more engaged.