12/9/2023 0 Comments Motion definition physicsYou may want to introduce the concept of a reference point as the starting point of motion. As you will learn in the Snap Lab, your description of motion can be quite different when viewed from different reference frames. You, as the reference frame, would be moving in the same direction as your other moving classmates. If you and your classmates left the room together, then your perspective of their motion would be change. If you remained seated as your classmates left the room, you would measure their movement away from your stationary location. You could also serve as a reference frame for others’ movement. You might say, “The teacher is moving toward the door.” Your reference frame allows you to determine not only that something is moving but also the direction of motion. You can also tell in what direction something is moving in the classroom. You can also tell if other things in the classroom are moving, such as your classmates entering the classroom or a book falling off a desk. Your motion as you walk to the door, can be measured against the stationary background of the classroom walls. In the classroom, the walls are not moving. Your classroom can be used as a reference frame. It is related to other English words, such as cinema (movies, or moving pictures) and kinesiology (the study of human motion). Explain that the word kinematics comes from a Greek term meaning motion. The reference frame is the coordinate system from which the positions of objects are described. (See Figure 2.2.) Thus, you can only know how fast and in what direction an object's position is changing against a background of something else that is either not moving or moving with a known speed and direction. To describe the position of a person in an airplane, for example, we use the airplane, not Earth, as the reference frame. In other cases, we use reference frames that are not stationary but are in motion relative to Earth. For example, a rocket launch would be described in terms of the position of the rocket with respect to Earth as a whole, while a professor’s position could be described in terms of where she is in relation to the nearby white board. Earth is often used as a reference frame, and we often describe the position of an object as it relates to stationary objects in that reference frame. More precisely, you need to specify its position relative to a convenient reference frame. How do you know something is moving? The location of an object at any particular time is its position. Even in inanimate objects, atoms are always moving. When you are resting, your heart moves blood through your veins. Everything from a tennis game to a space-probe flyby of the planet Neptune involves motion. Objects are in motion everywhere you look. Our study of physics opens with kinematics-the study of motion without considering its causes. What components are necessary for a definition of motion? Defining Motion Then compare and discuss definitions as a class. Ask the students to form pairs, and ask each pair to come up with their own definition of motion. Ask students to describe the path of movement and emphasize that direction is a necessary component of a definition of motion. Then bring in the concept of a numbered line as a way of quantifying motion. Lead them to the idea of a defined starting point. Then ask how they know the object has moved. Start by asking what position is and how it is defined.
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