# difference between cartesian and generalised coordinates

{\displaystyle \delta } The kinetic energy is a function only of the velocities vk, not the coordinates rk themselves. {\displaystyle \delta } Only two coordinates are needed instead of three, because the position of the bob can be parameterized by two numbers, and the constraint equation connects the three coordinates x, y, z so any one of them is determined from the other two. By contrast an important observation is. These vectors satisfy the two constraint equations. …, and ground, sothat the balls remain stationary is8​, and ground, sothat the balls remain stationary is​, Q. Still for the time-independent case, this expression is equivalent to taking the line element squared of the trajectory for particle k, and dividing by the square differential in time, dt2, to obtain the velocity squared of particle k. Thus for time-independent constraints it is sufficient to know the line element to quickly obtain the kinetic energy of particles and hence the Lagrangian.. δ In these examples, that variable is either arc length, Two generalized coordinates, two degrees of freedom, on curved surfaces in 3d. A logical choice of generalized coordinates to describe the motion are the angles (θ, φ). Also, in Lagrange's equations of the first kind, only the derivatives are needed. Only one generalized coordinate is needed to uniquely specify positions on the curve. The force of gravity acting on the masses is given by, where g is the acceleration of gravity. Second, this illustrates the key difference between generalized coordinates and the more ordinary coordinate systems that you're familiar with, e.g. r. When formulated in terms of generalized coordinates, this is equivalent to the requirement that the generalized forces for any virtual displacement are zero, that is Fi=0. in which (θ, φ) are the spherical polar angles because the bob moves in the surface of a sphere. …, Starting from rest, a particle moves on a circle withconstant angular acceleration a. The minimumcoefficient of friction between lower balls …, qual inmagnitude isoptions :1) 1 ÷ α^½2) 2^½ ÷ α^½3) 3^½ ÷ α^½4) 4^½ ÷ α^½​. y is the y-component of the applied force. δ where x are the Cartesian coordinates, q are the (redundant) internal coordinates. …, rce F. Theacceleration of the free end P is​, Write down the equation of rational motion. Now assume that each δrj depends on the generalized coordinates qi, i=1, ..., n, then. Kane shows that these generalized forces can also be formulated in terms of the ratio of time derivatives. In 2d polar coordinates (r, θ), The generalized momentum "canonically conjugate to" the coordinate qi is defined by. suggestions​, jo log kehte hain na main kuch nhi kar sakte unse waada h mera asaa samhe launga kehne ko majboor ho jaoge Jo Tu Kar SAKTA h woh koi aur nhi kar SAKTA What is the difference between Generalised co-ordinates and Degrees of freedom in classical mechanics? Basically, take the idea behind spherical or cylindrical (or polar) coordinates as taking your “straight grid lines” and placing them in some curved way in space. are the generalized forces acting on the system. In this case, we have. If the part AB is The value ofcoefficient of friction between rope and ground is (g = 10m/s)​, Three identical billiard balls each of mass 1 kg are placedas shown. A block of mass 9 Kg rests on a planemaking an angle of 160 with horizontal,Determine the component of the weight normalto the planAns.A. Usually, you start with Cartesian coordinates. D'Alembert's form of the principle of virtual work for the pendulum in terms of the coordinates x and y are given by, Using the parameter θ, those equations take the form. Only two numbers (, Physical quantities in generalized coordinates. The key to understanding how they differ is that the dot product (or metric) of two vectors is not simply the sum of squares of their components [or with a difference, for Minkowski geometry] anymore; it is instead something more complicated. Then, take arbitrarily squiggly lines instead, and those are generalized coordinates. which now both depend on time t due to the changing coordinates as the wire changes its shape. δ which illustrates the kinetic energy is in general a function of the generalized velocities, coordinates, and time if the constraints also vary with time, so T = T(q, dq/dt, t). The benefits of generalized coordinates become apparent with the analysis of a double pendulum. Notice time appears implicitly via the coordinates and explicitly in the constraint equations. {\displaystyle \delta } This shows that the parameter θ is a generalized coordinate that can be used in the same way as the Cartesian coordinates x and y to analyze the pendulum. Generalized coordinates are usually selected to provide the minimum number of independent coordinates that define the configuration of a system, which simplifies the formulation of Lagrange's equations of motion. spherical or cylindrical coordinates. The transformation between polar and Cartesian systems is given by following relations: r = √(x 2 + y 2) ↔ x = r cosθ, y = r sinθ. Generalized (or curvilinear) coordinates are other triplets of numbers which describe the same space, such as spherical or cylindrical coordinates. θ = tan-1 (x/y) What is the difference between Cartesian and Polar Coordinates? I know that they are not equal when we have non-holonomic equations of constraints. …, A uniform massive rope ABC has a length of 6 m. The ropeis held at rest by applying a force Fat an angle of 37° withthe horizontal. The upper ball is smooth. {\displaystyle \delta } In the case the constraints on the particles are time-independent, then all partial derivatives with respect to time are zero, and the kinetic energy is a homogeneous function of degree 2 in the generalized velocities. Two very different concepts here, with a point of connection. Suppose the wire changes its shape with time, by flexing. The principle of virtual work states that if a system is in static equilibrium, the virtual work of the applied forces is zero for all virtual movements of the system from this state, that is, Read more on Brainly.in - brainly.in/question/6444755#readmore, This site is using cookies under cookie policy. In the same way, the coefficient of Then the constraint equation and position of the particle are respectively. Let the forces on the system be Fj, j=1, ..., m be applied to points with Cartesian coordinates rj, j=1,..., m, then the virtual work generated by a virtual displacement from the equilibrium position is given by.