Which method is correct for this problem involving motion of

AI Thread Summary
The discussion centers on the analysis of electric forces acting on a particle Q in motion, particularly at the highest and lowest points of its trajectory. Participants agree that the two electric forces on Q are in the same direction when Q is at the top, but there is confusion regarding the diagram's accuracy and the conditions described. The tension in the string is noted to be zero at the top, with contributions from centripetal force, weight, and electric forces needing to be considered. There is debate about the minimum tension occurring when Q is at the bottom, with suggestions to clarify the method used. Overall, the execution of the methods discussed requires refinement to accurately represent the physical situation.
Sanchayan Dutta
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It may be that none of the answers are right.
For the first method, are the two electric forces on Q in the same direction, when Q is on top?
 
nasu said:
It may be that none of the answers are right.
For the first method, are the two electric forces on Q in the same direction, when Q is on top?
yes they are in same direction.
 
Do you think that your diagram represents the situation described in the problem?
I mean "particle B at the highest point".
 
The tension in the string is zero at the top for the given conditions.
Add the contributions to the tension (centripetal force, weight of the mass, and the two electrical forces
such that the tension is zero.
It might be easier to think of the acceleration at the top (m v^2 / R = weight + the two electrical forces)
 
Sanchayan Dutta said:
yes they are in same direction
They are not. Maybe, as nasu wonders, you are taking Q at the lowest point instead of the highest.
In your method 2, you write that the tension is minimum when Q is at the bottom. What makes you think that?
J Hann said:
Add the contributions to the tension (centripetal force, weight of the mass, and the two electrical forces such that the tension is zero
Seems to me that is exactly Sanchayan's method 1, but the execution was lacking.
 
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