Forces are fundamental to understanding how objects interact and change their state of motion. A force is a push or a pull applied to an object, always resulting from its interaction with another object. Understanding how forces work helps explain why objects move, stop, or remain still.
What Are Balanced Forces?
Balanced forces occur when multiple forces acting on an object are equal in strength and opposite in direction, resulting in a net force of zero. When forces are balanced, an object that is not moving will remain stationary. Similarly, an object that is already in motion will continue to move at a constant speed in a straight line if the forces acting on it are balanced.
For instance, a book resting on a table experiences a downward force from gravity and an equal, upward force from the table, keeping it still. In a tug-of-war game where neither side moves, the forces exerted by both teams are balanced. A car using cruise control on a flat road also demonstrates balanced forces, as the engine’s forward thrust balances air resistance and friction, maintaining a steady speed.
What Are Unbalanced Forces?
Unbalanced forces are not equal in magnitude or are not directly opposite in direction, leading to a non-zero net force. When unbalanced forces act on an object, they cause a change in its motion. This change can manifest as an increase in speed, a decrease in speed, or a change in direction.
For example, when you push a shopping cart, the force you apply is greater than the opposing forces like friction, causing the cart to accelerate. A falling apple is another instance of an unbalanced force; gravity pulls the apple downward with a force that is not entirely offset by air resistance, causing it to speed up as it falls. A car speeding up or slowing down also illustrates unbalanced forces, as the driving force or braking force is not equal to the resistance forces, leading to acceleration or deceleration.
How Net Force Determines Motion
The concept of net force is central to understanding how forces influence an object’s motion. Net force is the overall force acting on an object, calculated by summing all individual forces, considering both their strength and direction. This combined force determines whether an object’s state of motion will change. If the net force is zero, forces are balanced, and the object remains at rest or moves at a constant velocity. If there is a non-zero net force, forces are unbalanced, causing the object to accelerate in that direction.