A ball is thrown upward from an 80-ft tower with an initial vertical speed of 40 ft/s. If air resistance is ignored, the ball's speed when it reaches the ground will be
A) 67 ft/s.
B) 130 ft/s.
C) 120 ft/s.
D) 49 ft/s.
E) 82 ft/s.

Question

Quizplus · Accepted Answer

The ball's speed when it reaches the ground can be found using the conservation of energy principle. The initial potential energy plus initial kinetic energy equals the final kinetic energy. Solving for the final speed gives approximately 82 ft/s.

A Ball Is Thrown Upward from an 80-Ft Tower with an Initial