5.3 Torque

Identify the torques exerted on a rigid system.

• T orque results only from the force component perpendicular to the position vector from the axis of rotation to the point of application of the force.
• The lever arm is the perpendicular distance from the axis of rotation to the line of action of the exerted force.

Describe the torques exerted on a rigid system.

• T orques can be described using force diagrams.
  • i. Force diagrams are similar to free-body diagrams and are used to analyze the torques exerted on a rigid system.
  • ii. Similar to free-body diagrams, force diagrams represent the relative magnitude and direction of the forces exerted on a rigid system. Force diagrams also depict the location at which those forces are exerted relative to the axis of rotation.
• The magnitude of the torque exerted on a rigid system by a force is described by the following equation, where is the angle between the force vector and the position vector from the axis of rotation to the point of application of the force. BOUNDARY STATEMENT While AP Physics 1 expects students to mathematically manipulate the magnitude of torque using vector conventions, the direction of torque is beyond the scope of the course. TOPIC 5.4 Rotational Inertia