Motion and Speed Notes Motion is a change in position relative to another object. Motion can be measured by finding the distance an object moves in a given amount of time which determines the speed. Speed is measured in units of meters or kilometers (distance) and seconds or hours (time). The formula for finding speed is distance Speed= time If a force is applied to a moving object, the object can speed up, slow down or come to a stop. A force can also change the direction an object is moving. When a force changes the speed and the direction an object is moving we use the term velocity. Velocity is speed with direction. Acceleration is the term used to describe when an object changes its speed &/ or direction. An object that is falling to earth is subject to a change in acceleration of 2 9.8 m/s due to gravity.