Freely Falling Objects: Gravity at Work

  Objects fall. Unless something like wind or the hand of God interferes, they have a tendency to fall straight down until they hit the ground. This is a type of 1-dimensional motion in its simplest form: in a freely falling object problem, you can guarantee that all the acceleration of the object is due to gravity. You need to get very comfortable with acceleration due to gravity, for you will encounter it constantly for the remainder of your physics career. Besides which, we all experience the effects of gravity every day. Jump up and down. (Please read disclaimer) As you fall, you are experiencing acceleration due to gravity. You might as well get used to it.  

  Acceleration due to gravity can be represented by two different symbols, so be careful not to get confused. The symbols are "a" and "g" and are interchangeable. When represented, they will be in bold face or have a vector symbol above them, denoting that they have vector properties.  "a" is a generic symbol that can be used for any acceleration, gravitational or otherwise "g" is only used for acceleration due to gravity. If the problem is taking place on the planet earth, you can assume with confidence that the value of "a" or "g" (depending on notation) will be 9.8 m/s². If you are not on planet earth, the acceleration due to gravity will be specified. 

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