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--- 183_notes:system_choice [2014/10/29 22:04] – pwirving
+++ 183_notes:system_choice [2021/04/15 17:17] – [Choosing a System Matters] stumptyl
@@ Line 1: / Line 1: @@
+Section 7.7, 7.8 and 7.9 in Matter and Interactions (4th edition)
 ===== Choosing a System Matters =====
-Earlier, [[183_notes:energy_cons#multi-particle_systems|you read about a puzzle involving a ball falling to the Earth]]. We resolved this puzzle by introducing [[183_notes:potential_energy|the concept of potential energy]]. In these notes, you will look an example of a person lifting a box using different choices of system. The goal here is to demonstrate that the choice of a system matters.
+Earlier, [[183_notes:energy_cons#multi-particle_systems|you read about a puzzle involving a ball falling to the Earth]]. We resolved this puzzle by introducing [[183_notes:potential_energy|the concept of potential energy]]. **In these notes, you will look an example of a person lifting a box using different choices of system**. The goal here is to demonstrate that the choice of a system matters.
 ==== Lifting a box ===
@@ Line 25: / Line 27: @@
 === System 2: Box only ===
-Because the system is only a single particle, there's can be no potential energy. There is work done by both the person and the Earth, but they have opposite signs because the applied force and the gravitational force are in different directions.
+Because the system is only a single particle, there can be no potential energy. There is work done by both the person and the Earth, but they have opposite signs because the applied force and the gravitational force are in different directions.
   * System: Box; Surroundings: Earth and Person