April 20th, 2015, 11:43 AM  #1 
Senior Member Joined: Feb 2014 From: Louisiana Posts: 156 Thanks: 6 Math Focus: algebra and the calculus  Kinetic and potential energy of an object
I have a question about the conservation of energy. Imagine that there is an object on a level plane with zero kinetic energy and zero gravitational potential energy. Now imagine moving this object at some constant velocity in the ydirection for a few meters. Since it was moved at a constant velocity, there was no chance in kinetic energy, and thus no work was done. However, at the new height, there is nonzero potential energy mgh. If no work was done, how did the object go from having 0 kinetic energy and 0 potential energy to having 0 kinetic energy and mgh potential energy? Where am I going wrong?

April 20th, 2015, 12:14 PM  #2  
Math Team Joined: May 2013 From: The Astral plane Posts: 1,765 Thanks: 707 Math Focus: Wibbly wobbly timeywimey stuff.  Quote:
Dan  
April 20th, 2015, 01:13 PM  #3  
Senior Member Joined: Feb 2014 From: Louisiana Posts: 156 Thanks: 6 Math Focus: algebra and the calculus  Quote:
 
April 20th, 2015, 05:39 PM  #4  
Math Team Joined: May 2013 From: The Astral plane Posts: 1,765 Thanks: 707 Math Focus: Wibbly wobbly timeywimey stuff.  Quote:
$\displaystyle W_{net} = \Delta KE$ $\displaystyle W_{grav} + W_F = \Delta KE$ $\displaystyle mgh + W_F = 0$ $\displaystyle W_F = mgh = \Delta PE$ Thus work has been done on the object and increases the object's PE, as required. Dan  

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energy, kinetic, object, potential 
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