Tutorial: Circular motion III. Non-constant circular motion A skateboarder (mass 45 kg) starts from the top of a quarter pipe (i.e., a quarter circle) of radius 2.0 m, and when he is at the position shown below, he has a speed of 3.0 m/s. Your 30 goal is to calculate his centripetal acceleration, tangential acceleration, and the normal force acting on him when he is at the position shown. Friction at the wheels of the skateboard is negligible. To do this we will follow the problem solving strategy outlined in the previous pages. A. Draw a free body diagram on the skateboarder on the diagram to the right. B. Choose an xy coordinate system. Add this to your diagram above. Hint: What is the direction of the centripetal acceleration at the point indicated? C. Break up any forces not along the directions chosen and figure out the components in terms of the 30 angle shown. Draw the components on the figure and write down what they are equal to below. (For example, if you choose to break up the normal force, you might have Ny = N sin 309)