Forces can cause objects to slow down, so when a driver pushes on the brakes of a moving car, it slows down.
Forces can cause an object to speed up, slow down, change direction or change shape. In terms of speed changes, an object's acceleration rate is directly proportional to force applied, according to Newton's Second Law. For example, when one doubles the force applied to an object, its acceleration also doubles.
Conversely, an object's acceleration is inversely proportional to its mass. When one doubles the mass of an object, its acceleration is reduced by half, assuming the force applied remains constant.
In terms of shape changes caused by force, objects are divided into two types: elastic and plastic. Elastic objects return to their original shape after a force has been applied. Plastic objects, on the other hand, change shape and remain deformed after force is applied.