Torque

Definition

Torque is a measure of the rotational force applied to an object, which causes it to rotate around an axis. It is calculated as the cross product of the position vector from the axis of rotation to the point where the force is applied and the force vector itself. The direction of torque is determined by the right-hand rule and is crucial in understanding rotational motion and equilibrium.

5 Must Know Facts For Your Next Test

1. Torque is calculated using the formula $$ au = r imes F$$, where $$ au$$ is the torque, $$r$$ is the position vector, and $$F$$ is the force vector.
2. The units of torque are typically expressed in Newton-meters (N·m), indicating the amount of force applied over a certain distance.
3. The direction of torque is perpendicular to both the position vector and the force vector, following the right-hand rule.
4. Torque can cause an object to accelerate angularly, meaning it can change the object's rotational speed or direction.
5. In systems involving multiple forces, it’s essential to consider all torques to determine the overall rotational effect on an object.

Review Questions

• How does torque relate to rotational motion and what factors influence its magnitude?
  • Torque directly affects rotational motion by determining how quickly an object can rotate around an axis. Its magnitude depends on two key factors: the amount of force applied and the distance from the axis of rotation, known as the moment arm. The greater either of these factors, the larger the torque produced, leading to a more significant rotational effect.
• Discuss how torque can lead to conditions of rotational equilibrium in a system.
  • For a system to be in rotational equilibrium, the sum of all torques acting on it must equal zero. This means that any clockwise torques must be balanced by counterclockwise torques. By analyzing each force and its respective moment arm, one can determine if conditions for equilibrium are met, ensuring that there’s no net rotational acceleration.
• Evaluate how changing either the force applied or the distance from the axis affects torque and what implications this has in practical applications.
  • Changing the force applied or the distance from the axis significantly impacts torque, as it directly influences how effectively an object rotates. For instance, using a longer wrench increases torque even with minimal force due to greater moment arm distance. In practical scenarios like tightening bolts or operating machinery, understanding this relationship allows for efficient design and operation by maximizing torque while minimizing effort.

Related terms

Moment Arm: The perpendicular distance from the axis of rotation to the line of action of the force, which affects the magnitude of torque.

Rotational Equilibrium: A state where the sum of all torques acting on a body is zero, resulting in no net rotational acceleration.

Angular Momentum: The quantity of rotation of a body, which is affected by torque and can change when a net torque acts on an object.