Cornell Notes 2.2 Position and Speed October 18/19, 2011 Pages 53 and 55

Position An object’s position is its location at one instant in time. A position is always given compared to a fixed point, often its origin (starting point.) This origin is an example of a reference point. Motion is defined as a change in position ORIGIN (0,0)

Direction To give an exact position, you must give both the distance and the direction from the reference point. Left and right, along with up and down, are used in everyday life Scientists also use north, south, east, and west.

Length and Distance Distance is the amount of space between two points. Distance is measured in units of length.

Metric Prefixes Kilo- means “1000.” There are 1000 meters in a kilometer, 1000 grams in a kilograms, and 1000 baboons in a kilobaboon. Milli- means “1/1000.” There are 1000 millimeters in a meter (not the other way around.) Centi- means “1/100.” There are 100 centimeters in a meter. 1000!

Speed Speed is the most common measurement used to describe the motion of objects. Once you know an object’s speed, you can figure out how far it can go in a certain amount of time. You can also predict how long it will take to get somewhere.

Speed The speed of a bicycle is the distance it travels divided by the time it takes.

Metric Speed Although we use many different measures for speed, the one we will use most in class is meters per second (m/s) 1 m/s is equal to about 2.24 mph

Average Speed The speed found by dividing the total distance by the total time is the average speed.

Average vs Instantaneous Speed Instantaneous Speed is how fast you’re going right now – what it says on your speedometer. Average Speed is how fast you’ve been going over time (like for an hour or two.) For example, when you drive, you don’t always goes exactly 55 mph. Sometimes you do 60, sometimes 50. But if you cover 55 miles in one hour, that’s an average speed of 55 mph.

Relationships between distance, speed and time An equation can be used to calculate speed, distance, or time if two of the three values are known. Speed equals distance divided by time. (v=d/t)