Unformatted text preview: down) are now easy to write. If we locate the origin of our coordinates right at the earth's surface, and denote the positive direction as that which points upwards, we find that: x ( t ) =  gt 2 + v t + x Notice the  sign that arises because the acceleration due to gravity points downwards, while the positive positiondirection was chosen to be up. How does this relate to an object in free fall? Well, if you stand at the top of a tower with height h and let go of an object, the initial velocity of the object is v = 0 , while the initial position is x = h . Plugging these values into the above equation we find that the motion of an object falling freely from a height h is given by: x ( t ) =  gt 2 + h If we want to know, for instance, how long it takes for the object to reach the ground, we simply set x ( t ) = 0 and solve for t . We find that at t = the object hits the ground (i.e. reaches the position 0 )....
View
Full Document
 Fall '10
 DavidJudd
 Physics, Acceleration, Force, General Relativity

Click to edit the document details