#What is newtons first law of motion how to#

We can make the path as straight as we wish by choosing the time to release sufficiently short. For example, as the time to release gets shorter, the path of the stone changes less and less, but it keeps changing, gradually approaching a straight line tangent to the circle. A limit is a quantity that continues to change as time goes on, but it changes less and less and gradually approaches a definite value. As a result, after release, the stone simply continues this motion, in accordance with the first law, along the extension of the tiny straight line (path C).Īn example of a limit. As the time interval before release approaches zero, the stone's motion during that interval approaches an extremely short, horizontal straight line directed toward the left. We can never make the time interval zero, but we can make it as short as we wish. That little piece of the circle does not curve very much, and if we imagine the time interval before release gradually getting shorter, that piece of the circle also gets shorter, and straighter.

#What is newtons first law of motion how to#

To understand more clearly how to apply the first law, visualize the change in the position of the stone in the millisecond just before it is released (as in the right panel): during that time interval, the stone moves along a very short segment of the circle toward the left. Understanding the physics of motion involves developing an intuition and a set of principles, such as the first law of motion, which help us understand what we observe. The right panel shows how at least some experts visualize and think about this situation.Īpplying Newton's First Law. Understanding this situation fully involves developing one's physical intuition and learning how to visualize and think in a new way. This Demonstration illustrates that neither of these ideas, despite their intuitive reasonableness, are in accord with what happens in the real world. On the other hand, if we focus on the fact that the pull on the string by the boy towards the center of the circle keeps the stone moving in a circle at a constant distance from the boy at the center, it seems reasonable that once that pull disappears, the stone would move away from the center, along path D or E. As a result, it seems reasonable that the stone would move along path A or B. For example, the stone might tend to 'remember' the fact that it was previously moving in a circle. Newton's First Law and 'Intuition.' The first law and the way the stone moves after it is released seem to contradict certain 'intuitive' ideas about circular motion. (This includes objects at rest their speed is zero, so with no net external force, they continue to move at zero speed.) After the stone is released, it is no longer interacting with the string, and it then moves in a straight line at constant speed (as seen from above).

The first law says: If all the external influences on an object cancel out (that is, there is zero net external force on the object), the object will move at constant speed in a straight line. Isaac Newton's first law of motion applies to the stone's motion after release. In fact, this Demonstration illustrates the fundamental concept of differential calculus: the 'limit', which we explain below. The visual model in the right panel is in fact what at least some experts 'see' in their minds' eye, and this kind of model is very powerful for thinking about motion. This shows how the second part of the motion 'connects with' the first part. The right panel shows how to visualize this motion so as to understand it better: the curved path becomes straighter and straighter, and after release the stone continues to move along the same straight line path (C). But C is what happens in the 'real world'. Just on the basis of intuition, most people initially find all of the choices above at least somewhat reasonable.