So far we have used Newton's second law= ma to establish the instantaneous relation between the sum of the forces acting on a particle and the acceleration of that particle. Once the acceleration is known,the velocity (or position) is obtained by integrating the expression of the acceleration (or velocity). There are two situations in which the cumulative effects of unbalanced forces acting on a particle are of interest to us. These involve:
In this lecture we will consider the equations that result from integrating Newtons second law, F=ma, in time. This will lead to the principle of linear impulse and momentum. This principle is very useful when solving problems in which we are interested in determining the global effect of a force acting on a particle over a time interval Linear momentum We consider the curvilinear motion of a particle of mass, m, under the influence of a force F. Assuming that
is a vector equation that relates the magnitude and direction of the force vector, to the magnitude and direction of the acceleration vector. In the previous lecture we derived expressions for the acceleration vector expressed in cartesian coordinates. This expressions can now be used in Newton's second law, to produce the equations of motion expressed in cartesian coordinates
例题2-5求例题2-4中所示薄壁圆环在内压力 b p=2MPa作用下的径向应变和圆环直径的改变量。 已知材料的弹性模量E=210GPa p 解:在例题2-4中已经求出圆环在任一横截面 上的正应力=40MPa,若正应力不超过材料的比 例极限,则可按公式(2-6)算出沿正应力方向 (a) (即沿圆周方向)的线应变为
1. Current Regulations of Agricultural seed Production 2. (1)The Current Seed Law of P.R. China 3.(2)Registration and release of plant cultivars 4.(3) Plant Breeders right 5.()Requirements for the seed Enterprises: Capitalasset; Physical/technical conditions
General Approach to Electrochemical Experiments Identify assumptions Ditusion- ass tran sort +Identify suitable boundary conditions Solye linear diffusion equation (Fick's 2nd law -use Laplace transtorm
10.1 Federal Regulation of Medical Devices 10.1.1 The Law (including amendments) 10.1.2 Organization of FDA 10.1.3 Classification of Devices 10.1.4 Process of Assessment 10.1.4.1 510(k)Substantial Equivalence 10.1.4.2 Premarket Approval 10.1.5 Clinical Trials (Investigational Device Exemption) 10.1.6 Labeling 10.1.7 Tripartite Biocompatibility Guidance 10.1.8 Standards 10.1.9 Good Manufacturing Procedures 10.1.10 Good Laboratory Practices 10.2 Clinical Trial Design
Learning Objectives Describe the steps in the tax research process Explain how the facts affect the tax results Identify the sources of tax law and understand the authoritative value of each Use the tax services to research an issue
