Lesson 17 : Summary on The first Condition of Equilibrium.
- Static equilibrium refers to the condition where a system or particle is completely at rest, meaning there is no translational or rotational motion.
- In static equilibrium, all forces acting on the system are balanced.
- This balance implies that the upward forces cancel out the downward forces, and the forces to the left are balanced by the forces to the right. Although these forces are not necessarily identical in magnitude, they cancel each other out, resulting in no net force on the system.
- There are two primary conditions for equilibrium: translational and rotational.
- The first condition, known as translational equilibrium, occurs when the net external force acting on a body is zero.
- This means the body either remains at rest or moves with a constant velocity
- According to Newton’s second law, if the velocity (v) is constant, then the sum of external forces (∑Fext) must be zero. Thus, for translational equilibrium, the total linear momentum of the body remains constant over time.
- The second condition is rotational equilibrium, where the net external torque acting on a body is zero.
- This implies that the body does not rotate or rotates with a constant angular velocity.
- For rotational equilibrium, the sum of all external torques (∑τext) must be zero.
- These conditions ensure that the body remains in a stable state without any rotational acceleration.
- In practice, achieving static equilibrium requires careful analysis of both the magnitude and direction of all forces acting on the system.
- The forces must be balanced in all dimensions (x, y, and z) to ensure complete equilibrium.
- This analysis often involves examining objects within the x-y plane, but the principles apply to three-dimensional space as well.
- To illustrate, consider a stationary person or a car moving at a constant velocity.
- In both cases, the forces acting on the person or car sum up to zero, ensuring that they are in static or dynamic equilibrium, respectively.
- This means that there are no unbalanced forces causing acceleration in any direction, maintaining the stability of the system.