Question

A dense metal sphere is dropped from a 10-meter tower, and at the exact same time an identical metal sphere is thrown horizontally from the same height. If air friction is ignored, which statement below is true?
A. Both spheres land at the same time.
B. The thrown sphere lands before the dropped sphere.
C. The dropped sphere lands before the thrown sphere.
D. The horizontal speed of the thrown sphere will determine whether it will land first or not.

Answer 1

Answer:

A. Both spheres land at the same time.

Explanation:

The horizontal motion doesn't affect the vertical motion.  Since the two spheres have the same initial vertical velocity and same initial height, they land at the same time.

Answer 2

Answer:

A. Both spheres land at the same time.

Explanation:

If air resistance and friction are ignored, then both spheres land at the same time. Falling objects fall toward the center of the Earth with the same constant acceleration, independent of their mass, when they are defined to be in free-fall. For an object to be in free-fall, it has to be in a situation in which both air resistance and friction are considered negligible. This is true regardless of the direction of the fall.