Which requires more work, lifting a 25-kg. bag of cement 10 m. vertically, or lifting a 50-kg. bag 5 m.


Mo-mo-jo-jo , Wednesday, 11th of August 2010 08:15:24 PM

vertically?

a) 25-kg. bag.
b) 50-kg. bag.
c) Both 
Mo-mo-jo-jo
the same.

10 points to correct answer!
 
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Dipsy , Thursday, 12th of August 2010 03:38:45 PM

c) Same oh, same oh.  
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WE = Fs = Wh = mgh; where work energy is force F times distance s the  
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force acts over. In this case the force of lifting to height h overcomes  
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the weight W = mg of each bag of mass m. g = 9.81 m/sec^2 on average on  
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Earth is surface.  
 
Thus, for the m = 25 kg bag, we have WE = mgh = 25*9.81*10 = 2452.5  
kg-(m/sec)^2 (aka Newton-m)  
 
For m = 50 kg, we have WE = 50*9.81*5 = 2452.5 N-m.  
 
 
 
 
 

Rockchick , Friday, 13th of August 2010 10:10:09 AM

c) Both the same.  
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Gir , Saturday, 14th of August 2010 04:07:42 AM

Both examples would be exactly the same work.  
Gir
 
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The work done is mass times distance lifted.  
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This is the same in both cases.  
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So the answer is C>  
 
 
 
 
 

Angelina , Sunday, 15th of August 2010 12:44:00 AM

It would the weight not the distance that determines that It  
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stands to reason that carrying something half as heavy as something else  
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could be carried further because your muscles wont tire as quick  
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