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posted by  hates.physics on 11/4/2009 5:34:37 PM  |  status: Live  |  Earned Karma: 25

net work and kinetic energy

Course Textbook Chapter Problem Needs by
General Physics N/A N/A N/A 11/4/2009 at 6:00:00 PM
Question Details:
An object of mass 0.550 kg is lifted from the f loor to a height of 3.50 m at a constant speed.
How much work is done by the lifting force?
How much work is done by the Earth on the object?
What is the net work done on the object?
What is the change in kinetic energy of the object?
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posted by JamesD on 11/4/2009 7:21:00 PM  |  status: Live
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Response Details:
 The work done by the lifting force 
      W = F*s = mg*h = 0.55kg*9.8*3.5m = 18.865 J
The work done by the earth is equal to mgh = 18.865 J
The net work done  W = 18.865J
from law of conservation of energy
the change in kinetic energy = potential energy
   so ΔKE = 18.865J
I hope this helps! Best of luck with the rest of your coursework.
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