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How Pulleys Affect Force 
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#1
Oct608, 01:25 PM

P: 109

1. The problem statement, all variables and given/known data
A 100 gram mass is hanging vertically from a spring scale and exerts a certain force. Another 100 gram mass is set up in the following situation (there is a pulley, spring scale, mass, and ring stand holding up the spring scale): Do the weights on each setup exert equal forces on the spring scale, neglecting the weight and friction of the pulleys? 2. Relevant equations 3. The attempt at a solution I thought that I would have to separate the second one in to vectors to figure out if there is a difference. 


#2
Oct608, 01:32 PM

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In the one the tension goes straight up to the scale. In the other if there is a difference in the tension at the weight and the tension at the scale, what will the weight be doing? Will it be in motion? 


#3
Oct608, 03:44 PM

P: 109

When we did the experiment the only measurement we were told to make was reading the spring scale. In the first situation the spring scale read .98 N, while in the second situation the scale read .8N. However, my teacher said that the readings should have been the same the same in both situations, but that doesn't make sense.



#4
Oct608, 04:02 PM

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How Pulleys Affect Force
Oil the pulley next time? 


#5
Oct608, 04:28 PM

P: 109

Thank you for the reply.
So the measurement in Newtons should have been the same both times? Why is that? Don't you need to break down the force that the 100 g mass exerts into vectors to get the x any y directions of force? 


#6
Oct608, 04:33 PM

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#7
Oct608, 04:44 PM

P: 109

Wouldnt the mass being hung at an angle from the spring scale decrease the amount of force it exerts on the scale in horizontal direction?



#8
Oct608, 05:42 PM

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What angle? The force of the weight is along the tension translated back to the scale. If the scale is supporting with less force than the weight ... is the cable growing, is the weight in motion? Otherwise the sum of the forces are 0. 


#9
Oct608, 05:53 PM

P: 109

Thank you for your help thus far. 


#10
Oct608, 06:57 PM

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#11
Oct608, 10:53 PM

P: 109




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