Charged particles deflecting in a statics question.

AI Thread Summary
A particle with a mass of 2g and charge q is suspended and deflected by an equal and opposite charge held nearby, creating a 45° angle with the vertical when the particles are 25cm apart. The problem involves analyzing the forces acting on the suspended particle, including gravitational force and electrostatic force. The participant resolved forces using trigonometry and statics principles but initially struggled with identifying opposing forces. Clarification was provided regarding the interpretation of the problem, leading to two valid solutions based on different gravitational constants. The discussion emphasizes the importance of accurately understanding the problem's wording for effective problem-solving.
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[SOLVED] Charged particles deflecting in a statics question.

Homework Statement



A particle mass 2g and carrying a charge of q is suspended from a light, insulating thread. A second particle carrying an equal and opposite charge is held near to the first particle in the same horizontal plane and causes it to deflect. When the particles are separated by 25cm it is observed that the thread makes an angle of 45° to the vertical. By considering the forces acting on the suspended particle, find the magnitude of q.

Homework Equations


F=Qq/(4∏ε r^2)
Trigonometry
Statics


The Attempt at a Solution


I've assumed that the 25cm is measured between the particles before the deflection.
I've drawn a force diagram and resolved the forces relative to the force from the stationary particle. So 2gsin(45) is acting downwards, tension in in the string acts in opposition to the electrostatic force and 2gcos(45). I am at a loss as to what is acting in opposite to the 2gsin(45). I can take a photo of what I have if anyone isn't clear on what I've done.
 
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Your assumption does not correspond to the wording of the question.

Quote: "When the particles are separated by 25cm it is observed that the thread makes an angle of 45° to the vertical".
 
Ah. True. OK I have two answers now. They make sense, one for if g=9.81 and another for if g=the unit. Thank you very much.
 
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