Which object hits the ground first: a bullet fired horizontally or a bullet dropped from the same height?
This is a famous physics question posed to introductory physics students. The typical response would be the bullet that is dropped lands first because it has less distance to travel. Although this seems to make sense, the answer is wrong. In fact, both objects land at the same time. All objects are pulled toward the Earth by gravity and accelerated at a rate of –9.8 m/s2. This means that all objects fall at the same rate. If a bullet is given a horizontal velocity in addition to its downward acceleration due to gravity, it will continue to move across as it falls down – but it still keeps falling at –9.8 m/s2 just like the bullet that is dropped. Both the dropped bullet and the bullet fired horizontally fall at the same time; the added bonus for the fired bullet is that it travels horizontally as well. The strobe photograph shows one ball falling while the other ball is both falling and given a horizontal velocity. Notice at each time interval both balls have fallen the same distance.
