Here's why:
* Newton's First Law of Motion: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
* Balanced Forces: When multiple forces act on an object, but their vector sum is zero, they are considered balanced. This means the forces cancel each other out, resulting in no change in the object's motion.
Examples:
* A book on a table: Gravity pulls the book down, but the table exerts an equal and opposite normal force upwards. These forces are balanced, resulting in the book staying at rest.
* A hanging picture: The weight of the picture pulls it down, but the tension in the string holding it up exerts an equal and opposite force. Again, balanced forces.
Key Point: While there might be multiple forces acting on a body at rest, the crucial factor is that their combined effect (net force) is zero.
