Two identical objects start at the same height above level ground. Simultaneously, object A is dropped and object B is launched horizontally with a speed of 20 m/s.

Question

Two identical objects start at the same height above level ground. Simultaneously, object A is dropped and object B is launched horizontally with a speed of 20 m/s. Assume that air resistance is negligible.

a) Which object hits the ground first, or do they hit the ground at the same time?

b) Which object hits the ground with the greatest speed, or do they hit the ground with the same speed?

c) If the two objects started at a height of 5.0 m above the ground, how far apart would they land?

Answer 1

(a) they both hit the ground at the same time, as they have the same acceleration in that direction.

(b) they both hit the ground with the same vertical velocity, but object B has a horizontal (20 m/s) component that object A does not have.

(c) The relationship between falling distance at time is

5m = g·t²/2 (where the acceleration of gravity g = 9.82 m/s²) which means that it takes 10/9.82 = 1.0183 seconds for both objects to hit the ground. Since one them is moving away at 20 m/s, they will fall 20.367 m apart.