3) The force of gravity on a textbook is l8 N [down]. I. What is the net force on the book if it is held stationary in your hand? 2. Neglecting air resistance, what is the net force acting on the book if you suddenly remove your hand? 9) At one particular instant in its flight, a ball experiences a gravitational force Fg =15 N [down] and an air resistance force Fair above the horizontal]. Calculate the net force on the ball