What is rigid body movement

  • In contrast to a mass point, the points of application of forces must also be considered with a rigid body. - The Torque is defined as force x force arm:

The following applies to the direction of the torque:

Right-hand rule / right-hand screw rule (see sketch)



The direction of the angular velocity results from the direction of rotation according to the "right-hand screw rule" (see sketch).

  • Mass moments of inertia

    The mass moment of inertia I. depends on the mass and the body shape (distribution of the mass with respect to the axis of rotation).

  • Steiner's theorem

    The moment of inertia of a body when rotating about any axis B is related to the moment of inertia with respect to the parallel axis A through the center of gravity in the following relationship:

  • For the Rotational energy of a body:
  • The Angular momentum is defined as:
  • Torque and angular momentum change: A torque leads to an angular acceleration or a change in angular momentum: