Jamal is in a car travelling north. He looks out of his window and thinks that the cars around him are moving slowly. Ellen is in a car going south. She thinks that the northbound traffic is moving quickly. Explain why Jamal and Ellen have different ideas about the motion of the traffic. Maybe these terms will help: position, motion, reference point, speed, frame of reference MOTION
MOTION Where is the ___________? NO POINTING!!! The position of a place or an object is the location of that place or object We describe the position of something by comparing it to where we are.
MOTION Where is Rochester? We usually describe the location of a city compared to that of another city. A location to which you compare other locations is a reference point. Longitude and latitude is based on reference points.
What is distance? (n) The extent or the amount of space between two things. We measure distance depending on the information that we want. Straight line distance (flight) vs. total length of a certain path (hike) SI unit = meters (m) = 3.3 feet MOTION
What is motion? (n) The change of position over time. Do we need to see something move to know that motion has occurred? No. We can assume based upon starting and ending positions. MOTION
What is speed? (n) A measure of how quickly or slowly an object changes position. A faster object moves farther than a slower object over the same amount of time. MOTION
If you sit still in a chair, are you moving? It depends on the position and motion of the person watching you. If inside the room, no, you are not moving. If in space, yes, you are moving. This is known as frame of reference. MOTION
Frame of reference aka relative motion Consider this: You are sitting directly behind a bus driver. - Is the driver moving? - Is the street sign moving? An observer is on the sidewalk. - Is the driver moving? - Is the street sign moving? MOTION
REVIEW QUESTIONS What do you need to describe an object’s location? Describe how your position changes as you jump over an object. Give an example of how the apparent motion of an object depends on the observer’s motion. MOTION