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Unformatted text preview: Chapter 7 Study Guide for Moving Reference Frames 7.1 Uniformly moving reference frames Skill 7.1 Understand how measurements of position and velocity can differ depending on the reference frame in which they are taken. A reference frame is defined by a reference axis and a reference point from which motion is observed. Any reference frame with a reference axis that is at rest with respect to the surface of the Earth is called a stationary reference frame . Any reference frame with a reference axis that moves with constant velocity relative to the Earth is called a uniformly moving reference frame . Measurements of position and velocity differ depending on the reference frame in which they are taken. 7.2 Accelerating reference frames Skill 7.2 Understand the difference between inertial and non-inertial reference frames. An inertial reference frame is any reference frame moving with constant velocity (no acceleration) relative to the Earth. The law of inertia states that in an inertial reference frame, any isolated object at rest remains at rest, and any isolated object that is moving with some velocity continues to move at that velocity. Any reference frame for which the law of inertia does not hold is called a non-inertial reference frame . The law of inertia fails to hold for non-inertial reference frames because they are accelerating reference frames. Think about going around a corner in a car. You feel a force pushing you toward the outside of the curve, even though there is no force acting on you in that direction. The force you feel is a result of the fact that your reference frame is accelerated. 7.3 Linear momentum and reference frames Skill 7.3 Understand how the choice of reference frame affects the linear momentum of isolated systems. The linear momentum and kinetic energy of an isolated object are conserved in any inertial reference frame. The total linear momentum of an isolated system is conserved in any inertial reference frame. 1 Note: There is an important difference between the two preceding statements. The first one applies only to a single, isolated object. The second applies to a system consisting of many interacting objects. Look at checkpoints 7.5 and 7.6. 7.4 Energy and reference frames Skill 7.4 Understand how the choice of reference frame affects the kinetic energy of isolated systems. Even though changes in velocity are the same in different reference frames, changes in kinetic energy are not. The total kinetic energy of two elastically colliding objects is conserved in any inertial reference frame (think about the fact that kinetic energy is proportional to the square of the magnitude of velocity). The total energy of an isolated system is conserved in any inertial reference frame ....
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This note was uploaded on 05/04/2008 for the course PHYS 2054 taught by Professor Stewart during the Spring '08 term at Arkansas.
- Spring '08