Velocity of a charged particle as it approaches infinity

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SUMMARY

The discussion focuses on calculating the velocity of a charged particle as it approaches infinity, using the equations F = k(q1q2/r^2) and K = (mv^2)/2. The user initially attempts to solve the problem by calculating the net force exerted by multiple charges and equating it to kinetic energy. However, the user encounters a discrepancy between their calculated answer and the correct answer, indicating a misunderstanding of the relationship between force and energy. The discussion emphasizes the need for alternative problem-solving approaches in physics.

PREREQUISITES
  • Understanding of Coulomb's Law (F = k(q1q2/r^2))
  • Familiarity with kinetic energy formula (K = (mv^2)/2)
  • Basic vector addition for force components
  • Concept of limits in physics as a particle approaches infinity
NEXT STEPS
  • Explore alternative methods for solving physics problems involving multiple charges
  • Study the concept of energy conservation in electrostatics
  • Learn about the implications of limits in particle physics
  • Investigate common pitfalls in multiple-choice physics questions
USEFUL FOR

Students studying physics, particularly those focusing on electrostatics and energy concepts, as well as educators looking for insights into common student misconceptions in problem-solving.

Nasir Jones
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Homework Statement


shit_zps1gi9n06p.png


Homework Equations


F = k(q1q1/r^2)
K = (mv^2)/2

The Attempt at a Solution


I got number 18 easy enough, number 19 seems simple but I'm not getting the right answer. I'm calculating Force exerted by each charge on the new charge using F = k(q1q1/r^2) for the three charges, adding the X and Y components together, setting the net force equal to (mv^2)/2 and solving for v. The answer I get is C, but the correct answer is A. Not sure why.
 

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Nasir Jones said:
setting the net force equal to (mv^2)/2
A force cannot be said to be equal to a quantity of energy.
 
The writers of multiple choice problems sometimes determine all the mistakes the problem solver might make and include these wrong answers as choices. You should take another approach to solving this problem. Any one of several will work.
 

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