One person weighs 70 kg and rides a lightweight bicycle on a flat road. the weight of the bicycle itself is neglected, and the ground friction on the bicycle is ignored. the bicycle has a wheel radius of 32 cm and the pedal has a radius of rotation of 16 cm. if the person continues to apply 20 n of force on the pedal (the direction of the force is perpendicular to the pedal radius), let the bicycle accelerate from the standstill. when the pedal turns 50 turns, what is the speed of the bicycle? (ignore air resistance during acceleration)