* Newton's Second Law: The fundamental relationship between force, mass, and acceleration is given by Newton's Second Law: F = ma.
* Acceleration, not velocity: This law states that force is directly proportional to the acceleration of an object, not its velocity. Acceleration is the rate of change of velocity.
* Examples:
* Constant Velocity: A car moving at a constant speed on a straight road has zero acceleration even though a force (from the engine) is acting on it to overcome friction. The force is maintaining the constant velocity, not directly causing it.
* Projectile Motion: A ball thrown upwards experiences a constant force (gravity) acting on it. However, its velocity changes: it slows down going up, momentarily stops at the peak, and speeds up going down. The force is causing the change in velocity (acceleration), not the velocity itself.
In summary:
* Force causes changes in velocity (acceleration).
* If a force is applied constantly, the velocity will change proportionally.
* If the force is zero, the velocity will remain constant (unless other forces are present).
