How do electric charges interact?

Which two statements are true about a system? 1. a system is a group of objects analyzed as one unit. 2. energy that moves across system boundaries is conserved. 3. there’s only one way to define the boundaries of a system. 4. all systems are made by humans.

Which the following is a common trait in a four year college

When your working with the passage-based reading questions on the psat do all of the following except. a)make sure you read each question throughly. b) try to answer each question before you look at the answers. c) plan to spend most of your time reading the passage. d) make sure your answer choice is the most correct number me