Determine (a) the speed with which the train needs to travel on a curved section of the track if the magnitude of the side force to be felt by a passenger of weight � in a standard car with no tilt is 0.20�, (b) the required angle of tilt � if the passenger is to feel no side force when the train is traveling at 180 km/h. Notice that a side force is defined here as a force that is parallel to the floor of the car; and the rated speed of a curved section of track is defined as the speed at which a train should travel if no lateral friction force is to be exerted on its wheels.