* Forces can cause an object to stop moving. This is true if the force is applied in the opposite direction of the object's motion. Think of a car braking – the friction force from the brakes opposes the car's motion and brings it to a stop.

* Forces can also change the direction of motion. A force applied at an angle to the object's path will cause it to change direction. Think of a ball being hit by a bat, or a car turning a corner.

* Forces can also cause an object to start moving. If an object is at rest, a force can make it move. Think of pushing a box across the floor.

Key Point: Forces are interactions that can cause changes in an object's motion. This includes starting, stopping, or changing the direction of motion.