• Physics has been studied for thousands of years but not until comparatively recently was our modern understand of motion established.
• Two individuals who greatly contributed to this field were Galileo Galilei and Isaac Newton.
• The study of motion is in general called mechanics, but is customarily divided into two more parts, called kinematics and dynamics.
• Objects which move without rotating are called translational motion.
• The average speed of an object is the distance traveled divided by the time it takes to travel the distance.
• It is important to specify the motion of an object as well as its speed because it is a vector quantity.
• Using east, west, and etc. is not so effective in physics therefore we draw a coordinate axis to determine positives and negatives.
• Velocity is composed of both magnitude and direction and it thus becomes a vector quantity but speed on the other hand is only a scalar qty.
• The magnitude of the instantaneous speed and the magnitude of the instantaneous velocity are always the same.
• Instantaneous velocity is at any given moment defined as the average velocity over an indefinitely short time interval.
• If an object moves at a uniform rate then its instantaneous velocity will be the same as its average velocity.
• Average velocity is the rate of change of velocity divided by the time taken to make this change.
• When an object's speed is decreasing it is said to be decelerating, which is not always a negative number, because it depends on direction.