* Force and Motion: Force causes changes in an object's *motion*. This motion can be described in terms of both speed (how fast the object is moving) and direction (which way the object is moving).
* Changing Direction: A force can change the direction of an object's motion without changing its speed. Imagine pushing a ball horizontally across a frictionless surface. The force changes the direction of the ball's motion (it curves), but its speed might remain constant.
* Circular Motion: A classic example is an object moving in a circle at a constant speed. The object is constantly accelerating towards the center of the circle (due to a force pointing inwards). The speed remains constant, but the direction is changing, resulting in a changing velocity.
Key Point: Force causes a change in *velocity*, which is a combination of speed and direction. Changing direction alone is a change in velocity, even if the speed stays the same.
