A classmate throws a 1.3-kg book from a height of 1.2 m above the ground straight up into the air. The book reaches a maximum height of 3.9 m above the ground and begins to fall back. Assume that 1.2 m above the ground is the reference level for zero gravitational potential energy.
(a) Determine the gravitational potential energy of the book when it hits the ground.
(b) Determine the velocity of the book just before hitting the ground.