Find the expressions for the unit vectors in cylindrical coordinate system, p 8,9,2. find the time-derivative of each. hints: unit vector rho is defined in (x, y) plane. remember that ã  . ñ is perpendicular to a the easiest way to find ñ is to express through ñ and add 90 degrees. 8

Complete these sentences. if a roller coaster train has a potential energy of 1,500 j and a kinetic energy of 500 j as it starts to travel downhill, its total energy isj. once the roller coaster train gets closer to the bottom of the hill, its kinetic energy increases to 1,100 j, and its potential energy decreases to j. when the train reaches the bottom of the track and is traveling along the ground, its kinetic energy isj.