An accelerometer is a device used to measure linear acceleration without an external reference. The main idea has already been illustrated in the previous lecture with the example of the boy in the elevator. Clearly, if we know the weight of the boy when the acceleration is zero, we can determine from the reading on the scale the value of the acceleration. In summary, the acceleration will produce an inertial force on a test mass, and this force can be nulled and measured with precision. Below we have sketch of a very simple one axis accelerometer

In this lecture, we will start from the general relative motion concepts introduced in lectures D11 and D12. and then apply them to describe the motion of 2D rigid bodies. We will think of a rigid body as a system of particles in which the distance between any two particles stays constant. The term 2-dimensional implies that particles move in parallel planes. This includes, for instance, a planar body moving within its plane

In this lecture, we will revisit the principle of work and energy introduced in lecture D7 for particle dynamics, and extend it to 2D rigid body dynamics. Kinetic Energy for a 2D Rigid Body We start by recalling the kinetic energy expression for a system of particles derived in lecture D17

第一章 大学之魂 第二章 青春在呼号 第三章 仁爱，天地最美 第四章 爱是难的 第五章 向往自由 第六章 寻找良知 第七章 星空让人敬畏 第八章 乡愁与家园 第九章 为了忘却的记忆 第十章 英雄不仅是神话 第十一章 坚忍的山峦 第十二章 希望的红帆 第十三章 审视自我 第十四章 反讽与幽默 第十五章 诗意地栖居 第十六章 回归大自然

本书不是也并不打算成为一本社会科学著作，而是要对冷战之后全球政治的演变作出解释。他渴望提出一个对学者有意义的和对于决策者有用的看待全球政治的框架或范式。对于其意义和有用性的检验不在于看它是否说明了正发生于全球政治中所有的事情，它显然做不到这一点，而在于它是否比其他任何可供选择的范式提供了一个更有意义的和更有用的观察国际发展的视角

第一章 大学之魂 第二章 青春在呼号 第三章 仁爱，天地最美 第四章 爱是难的 第五章 向往自由 第六章 寻找良知 第七章 星空让人敬畏 第八章 乡愁与家 第九章 为了忘却的记忆 第十章 英雄不仅是神话 第十一章 坚忍的山峦 第十二章 希望的红帆 第十三章 审视自我 第十四章 反讽与幽默 第十五章 诗意地栖居 第十六章 回归大自然

In lecture D9, we saw the principle of impulse and momentum applied to particle motion. This principle was of particular importance when the applied forces were functions of time and when interactions between particles occurred over very short times, such as with impact forces. In this lecture, we extend these principles to two dimensional rigid body dynamics. Impulse and Momentum Equations Linear Momentum In lecture D18, we introduced the equations of motion for a two dimensional rigid body. The linear momen- tum for a system of particles is defined

In this lecture, we will particularize the conservation principles presented in the previous lecture to the case in which the system of particles considered is a 2D rigid body. Mass Moment of Inertia In the previous lecture, we established that the angular momentum of a system of particles relative to the center of mass, G, was

A pendulum is a rigid body suspended from a fixed point (hinge) which is offset with respect to the body's center of mass. If all the mass is assumed to be concentrated at a point, we obtain the idealized simple pendulum. Pendulums have played an important role in the history of dynamics. Galileo identified the pendulum as the first example of synchronous motion, which led to the first successful clock developed

In this lecture, we will derive expressions for the angular momentum and kinetic energy of a 3D rigid body. We shall see that this introduces the concept of the Inertia Tensor. Angular Momentum We start form the expression of the angular momentum of a system of particles about the center of mass