Ideas about the motion of falling objects date back long before modern theories of gravitation. A common idea of the time was that a projectile rises in a straight line until it runs out of ‘impetus’, at which point it falls to the ground (1); the heavier an object, the more rapidly it would fall.
The Italian scientist Galileo Galilei (1564–1642) designed an experiment in which a ball rolling down a slope hit a series of bells. By adjusting their positions, he made the bells ring at regular intervals (2), showing that the rolling ball had a constant acceleration (sometimes called ‘diluted gravity’). Galileo showed that all free-falling objects have the same acceleration and deduced that a projectile moves with constant horizontal velocity combined with a constant vertical acceleration (3).
Your organisation does not have access to this article.
Sign up today to give your students the edge they need to achieve their best grades with subject expertise
Subscribe