In fact, we can work out how you need to steer the skateboard. Tracker has a nice feature that we'll call 'force arrows'. These arrows show you how much force acts on an object at every instant, and in which direction the force acts. So for example, if you were to kick a ball into the air, while the ball was mid-flight, this arrow would always point down and be the same length, even though the ball is moving forward. That's because the only force acting on the ball is gravity, which pulls it straight down, and acts with a constant strength. (For those of you who've studied physics, these arrows denote the acceleration of the center of mass, which by Newton's second law is proportional to the net force acting on the skateboard.)

Smile and wave – Feel free to look around at all the other people at the skatepark that stood by and marveled at your new-found accomplishments (all one of them). I’m sure by this point you’ll be picking up roses that are being thrown at your feet, and taking a well-deserved bow as they begin to chant your name. Take it all in, thank the crowd for their undying affection, and then go get a snow-cone. You deserve it, champ.
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