galileo galilei proved that heavy and light objects fall at the same speed.
galileo galilei proved that heavy and light objects fall at the same speed.
who proved that heavy and light objects fall at the same speed?
galileo galilei
the ancient greek philosopher aristotle had the view that all objects have a natural place in the universe: that heavy objects (such as rocks) wanted to be at rest on the earth and that light objects like smoke wanted to be at rest in the sky and the stars wanted to remain in the heavens. he thought that a body was in its natural state when it was at rest, and for the body to move in a straight line at a constant speed an external agent was needed continually to propel it, otherwise it would stop moving. galileo galilei, however, realised that a force is necessary to change the velocity of a body, i.e., acceleration, but no force is needed to maintain its velocity. in other words, galileo stated that, in the "absence" of a force, a moving object will continue moving. (the tendency of objects to resist changes in motion was what johannes kepler had called "inertia".) this insight was refined by newton, who made it into his first law, also known as the "law of inertia"—no force means no acceleration, and hence the body will maintain its velocity. as newton's first law is a restatement of the law of inertia which galileo had already described, newton appropriately gave credit to galileo.
newton's laws of motion
the equivalence principle, explored by a succession of researchers including galileo, loránd eötvös, and einstein, expresses the idea that all objects fall in the same way, and that the effects of gravity are indistinguishable from certain aspects of acceleration and deceleration. the simplest way to test the weak equivalence principle is to drop two objects of different masses or compositions in a vacuum and see whether they hit the ground at the same time. such experiments demonstrate that all objects fall at the same rate when other forces (such as air resistance and electromagnetic effects) are negligible. more sophisticated tests use a torsion balance of a type invented by eötvös. satellite experiments, for example step, are planned for more accurate experiments in space.
gravity