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所在平台: Udemy |
课程主页: https://www.udemy.com/course/force-and-newton-laws-of-motion/
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这门Coursera课程“理解力和牛顿运动定律”深入探讨了经典力学的基石——牛顿运动定律。 课程始于对运动学中描述物体直线运动的固有局限性的回顾，即我们已经了解了位置、速度和加速度，也区分了匀速和非匀速运动。然而，这些描述并没有触及到“是什么导致了运动？为何物体的速度会随时间改变？运动是否都需要一个原因？如果需要，这个原因的本质又是什么？”这些根本性问题。本课程旨在解答这些关键疑问。 课程的核心内容将围绕伊萨克·牛顿提出的三条运动定律展开，它们阐述了作用在物体上的力与物体运动之间的关系。 * **牛顿第一定律：惯性定律** * 该定律指出，除非受到外力的作用，否则静止的物体将保持静止，运动的物体将继续以恒定的速度沿直线运动。 * 在经典牛顿力学中，静止和匀速直线运动并没有本质区别，它们可以被看作是同一运动状态在不同参照系下的表现。 * 惯性定律最早由伽利略·伽利莱提出，并由勒内·笛卡尔推广。虽然它是经典力学的出发点，但对未经训练的人来说并不显而易见。 * 亚里士多德力学和日常经验认为，不受推力作用的物体会趋于静止。伽利略通过斜面滚下球体的实验推导出了惯性原理。 * 对于伽利略来说，惯性原理是他科学探索的核心：他需要解释地球在自转并绕太阳公转时，我们为何感觉不到这种运动。惯性原理提供了答案：由于我们与地球一同运动，并且我们倾向于保持当前的运动状态，所以地球在我们看来是静止的。 * 与直观感受不同，惯性定律曾是一个重大的科学争议点。牛顿在完善其理论时，能够精确解释地球运动中存在的微小偏差，这些偏差是由地球表面运动并非理想匀速直线运动引起的（例如，旋转运动的影响）。 * 在牛顿的表述中，物体不受推力时会趋于静止的普遍观察，被归因于存在不平衡的力（如摩擦力和空气阻力）作用于物体上。 课程将通过对这些现象的深入分析，帮助学员理解力的概念以及牛顿运动定律在解释和预测物体运动中的核心作用。
In Kinematics course we described motion of an object along a straight line path in terms of its position , velocity and acceleration. We also saw that motion is of two types uniform and non uniform. But we did not discuss what causes motion? Why does the speed of an object change with time ? Do all motion require cause ? If so then what is the nature of this cause? Answer to these critical questions we seek to answer through this course.Newton's laws of motion, three statements describing the relations between the forces acting on a body and the motion of the body, first formulated by English physicist and mathematician Isaac Newton, which are the foundation of classical mechanics.Newton's first law: the law of inertiaNewton's first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. In fact, in classical Newtonian mechanics, there is no important distinction between rest and uniform motion in a straight line; they may be regarded as the same state of motion seen by different observers, one moving at the same velocity as the particle and the other moving at constant velocity with respect to the particle. This postulate is known as the law of inertia.The law of inertia was first formulated by Galileo Galilei for horizontal motion on Earth and was later generalized by René Descartes. Although the principle of inertia is the starting point and the fundamental assumption of classical mechanics, it is less than intuitively obvious to the untrained eye. In Aristotelian mechanics and in ordinary experience, objects that are not being pushed tend to come to rest. The law of inertia was deduced by Galileo from his experiments with balls rolling down inclined planes.For Galileo, the principle of inertia was fundamental to his central scientific task: he had to explain how is it possible that if Earth is really spinning on its axis and orbiting the Sun, we do not sense that motion. The principle of inertia helps to provide the answer: since we are in motion together with Earth and our natural tendency is to retain that motion, Earth appears to us to be at rest. Thus, the principle of inertia, far from being a statement of the obvious, was once a central issue of scientific contention. By the time Newton had sorted out all the details, it was possible to accurately account for the small deviations from this picture caused by the fact that the motion of Earth's surface is not uniform motion in a straight line (the effects of rotational motion are discussed below). In the Newtonian formulation, the common observation that bodies that are not pushed tend to come to rest is attributed to the fact that they have unbalanced forces acting on them, such as friction and air resistance.
