What is the Distance of Closest Approach Between Two Point Charges?

  • Thread starter purduegirl
  • Start date
  • Tags
    Approach
In summary, the conversation discusses the use of Coulomb's Law and the Law of Universal Gravitation to calculate the distance of closest approach between two point charges. The individuals in the conversation suggest using conservation of energy and the equation U = K*[q*q/r] to find the distance at which the kinetic energy is converted to potential energy. The final answer is determined to be 0.404 m.
  • #1
purduegirl
74
0

Homework Statement



Distance of Closest Approach
Use the similarity between Coulomb's Law and the Law of Universal Gravitation to calculate the distance of closest approach between a point charge of +3.40 × 10-6 C, which starts at infinity with kinetic energy of 8.70 J, and a fixed point charge of +1.15 × 10-4 C. Assume that the moving charge is aimed straight at the fixed point charge.
 
Physics news on Phys.org
  • #2
Just use conservation of energy. What's KE+PE at infinity? At closest approach, KE=0, since the point charge has stopped. But the total energy hasn't changed, right?
 
  • #3
I don't understand. Initially total energy and ending with total potential correct? How is this solved?
 
  • #4
take the two point charges as system! now all the Columbian and gravitational forces are internal forces and hence mechanical energy is conserved.

just use KEinitial + PEinitial = KEfinal + PEfinal

find PEfinal and use it to find the distance at that time
 
  • #5
Okay, i knew total energy is conserved. for anyone who needs it in the future, the closest distance of approach is when all kinetic energy is converted to potential energy. the problem can be solved using this equation: U = K*[q*q/r] where U = potential energy, K = coulomb's constant (8.9875E9), the q's are the respective charges of the particles, and r = distance of closest approach.
Notice that it is just r instead of r squared. this is enegry instead of charge force.
 
  • #6
Is the answer to this problem 0.404 m? Thanks
 

FAQ: What is the Distance of Closest Approach Between Two Point Charges?

What is the closest approach problem?

The closest approach problem, also known as the minimum distance problem, is a mathematical problem that involves finding the nearest distance between two points or objects.

How is the closest approach problem solved?

The closest approach problem can be solved using various mathematical techniques such as calculus, geometry, and optimization algorithms. The specific method used depends on the specific scenario and data available.

What are some real-world applications of the closest approach problem?

The closest approach problem has various applications in fields such as astronomy, physics, engineering, and computer science. It is used to calculate the shortest distance between celestial bodies, design optimal flight paths for spacecraft, and optimize the routing of vehicles in transportation networks, among others.

What are the main challenges in solving the closest approach problem?

The main challenges in solving the closest approach problem include dealing with complex and high-dimensional data, accounting for uncertainties and errors in measurements, and optimizing for multiple variables simultaneously.

Are there any real-world examples of the closest approach problem being solved?

Yes, there are many real-world examples of the closest approach problem being solved. For instance, NASA used the closest approach problem to design the trajectory for the Voyager 2 spacecraft's flyby of Neptune, which resulted in the closest approach of any spacecraft to the planet to date.

Similar threads

Back
Top