An object in equilibrium has a net force of Static equilibrium describes an object at having equal and balanced forces acting upon it. Dynamic equilibrium describes an object in having equal and balanced forces acting upon it.
The correct answer and explanation is:
Correct Answer:
An object in equilibrium has a net force of zero. Static equilibrium describes an object at rest having equal and balanced forces acting upon it. Dynamic equilibrium describes an object in motion having equal and balanced forces acting upon it.
Explanation:
Equilibrium in physics refers to a state in which all the forces acting on an object are balanced, resulting in no net force. This means that the total vector sum of all the forces equals zero. When there is zero net force, Newton’s First Law of Motion applies: an object at rest remains at rest, and an object in motion continues moving with the same velocity unless acted upon by an unbalanced force.
There are two main types of equilibrium: static and dynamic.
In static equilibrium, the object is not moving at all. It is at rest, and all the forces acting on it cancel each other out. For example, a book lying still on a table experiences a downward gravitational force balanced by an upward normal force from the table. Because the net force is zero, the book remains stationary.
In dynamic equilibrium, the object is moving, but it moves with a constant velocity. This means the forces acting on the object are still balanced, and no acceleration occurs. A good example is a car cruising on a straight road at constant speed, where the engine force is balanced by air resistance and friction. Since there is no net force, the motion continues steadily.
In both cases, the key feature is that the net force is zero. The difference lies in whether the object is stationary (static) or moving at constant speed in a straight line (dynamic). Understanding equilibrium helps explain and predict how objects behave under the influence of various forces in both rest and motion.