Key Concepts:
* Newton's First Law of Motion (Law of Inertia): 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 a net force*.
* Constant Velocity: Means the object is moving at a steady speed in a straight line. No changes in speed or direction.
* Net Force: The overall force acting on an object. It's the vector sum of all individual forces.
Forces on an Object at Constant Velocity
* Net Force is Zero: For an object to move at constant velocity, the net force acting on it *must* be zero.
* Balanced Forces: This means all the forces acting on the object are balanced. For every force in one direction, there's an equal and opposite force.
Examples:
* A car cruising down a straight highway at a constant speed: The engine's forward force is balanced by air resistance and friction from the road.
* A skydiver reaching terminal velocity: The force of gravity pulling the skydiver down is balanced by the air resistance pushing upwards.
Important Note: Even though the net force is zero, there *can* still be individual forces acting on the object. These forces just need to be balanced.
