A 004-Kg Ball Is Thrown from the Top of a 30-M

A 0.04-kg ball is thrown from the top of a 30-m tall building (point A) at an unknown angle above the horizontal. As shown in the figure, the ball attains a maximum height of 10 m above the top of the building before striking the ground at point B. If air resistance is negligible, what is the value of the kinetic energy of the ball at B minus the kinetic energy of the ball at A (K_B − K_A) ?

A) 12 J
B) −12 J
C) 20 J
D) −20 J
E) 32 J