Big history (3)

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Big history(3),Stars,Outline,The forming of galaxies,The Life cycle of stars,The rotation of rigid body,Solar system,The forming of universe structure,James Jeans(18771946).,The cause of universe structure,Gravitational instability,turbulence,Elliptical galaxy,Spiral galaxy,Nuclear fusion,White dwarf and neutron star,Angular momentum,The angular momentum of a particle respect to one point,The rotational inertia,Definition,A continuous body:,the moment of inertia of one rigid body is determined by its shape,the position of the axis and the density distribution,The moment of inertia of rod with its mass distributed uniformly and a perpendicular axis through one of its ends(its length l),o,x,z,dx,dm,x,Solution:,Angular momentum of one rigid body,z,d,Torque,（力矩）,In the plane that is perpendicular to the axis,we define torque as the cross product of the position vector and the normal component of the force respect to the axis,m,i,z,Newtons second law for rotation,（转动定律）,:,The conservation law of angular momentum,The angular momentum is a constant,provided the net torque on the rigid body is zero.,The solar system,The Life of sun,