Electrostatics Homework (Basic) HELP PLEASE~

In summary, two identical conducting spheres with an initial positive net charge attract each other with an electrostatic force of 0.0898 N at a center-to-center separation of 39.6 cm. After being connected by a thin conducting wire and then separated again, the spheres repel each other with an electrostatic force of 0.0337 N. To determine the initial charges on the spheres, we can use the equations for centripetal force and electrostatic force to find Q1 and -Q2. Then, by joining the spheres with a wire and separating them, we can find the charge on each sphere. From there, we can calculate the exact values for Q1 and Q2 in nanoCoulombs.
  • #1
roseyramos
1
0

Homework Statement


Two identical conducting spheres, fixed in place, attract each other with an electrostatic force of 0.0898 N when their center-to-center separation is 39.6 cm. The spheres are then connected by a thin conducting wire. When the wire is removed, the spheres repel each other with an electrostatic force of 0.0337 N. Of the initial charges on the spheres, with a positive net charge, what was (a) the negative charge in coulombs on one of them and (b) the positive charge in coulombs on the other?




A particle of charge Q is fixed at the origin of an xy coordinate system. At t = 0 a particle (m = 0.931 g, q = 4.49 µC is located on the x-axis at x = 16.0 cm, moving with a speed of 36.1 m/s in the positive y direction. For what value of Q (in μC) will the moving particle execute circular motion? (Neglect the gravitational force on the particle.)


Homework Equations







The Attempt at a Solution


So centripal force is

Fc=m•a=m•v²/R

And the electrostatic force is

Fe = kQq/R²

They are equal.


I need to get the answer is nanoCouloumbs. When I set these equations equal I get Q=481, but I have to remember that it's negative. The answer is supposed to be in NanoCoulombs, so I don't know if I'm correct and am typing it in wrong or I am way off. It's for one of the online physics homework thing we use at USD, so there's no way for me to know if I'm way off or almost there.

For part A, some other students think it's impossible, but the website is asking for an exact number for each one. I thought I did that one right as well, but what I'm getting is not correct. Can anyone help?
 
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  • #2
Hi roseyramos,
Welcome to PF.
Let Q1 and -Q2 be the charges on the spheres. Using the relevant formula find -Q1*Q2.
When you join them by a wire and separate to the original position, the charge on each sphere will be (Q1 - Q2)/2.
Again using the relevant find [(Q1 - Q2)/2.]^2.
Using these values find Q1 and Q2
 
  • #3



I would recommend approaching this problem by setting up the equations for the electrostatic force and the centripetal force and then solving for the unknown charges. It is important to remember to use the correct units and to consider the sign of the charges. It is also helpful to draw a diagram to visualize the situation. If you are getting a different answer than what is expected, double check your calculations and make sure you are using the correct values for constants such as k. Additionally, it may be helpful to discuss the problem with a classmate or a TA to ensure that you are on the right track. Remember to always show your work and explain your reasoning to receive full credit for your answer. Good luck!
 

1. What is electrostatics?

Electrostatics is the branch of physics that studies the behavior and properties of stationary electric charges.

2. What are some common examples of electrostatics?

Some common examples of electrostatics include lightning, static cling, and the attraction or repulsion between two charged objects.

3. How does electrostatics differ from electromagnetism?

Electrostatics deals with stationary charges, while electromagnetism deals with moving charges and their interaction with magnetic fields.

4. What is the basic equation for electric force?

The basic equation for electric force is F = k(q1q2)/r^2, where F is the force, k is the Coulomb's constant, q1 and q2 are the charges of the objects, and r is the distance between them.

5. How does the presence of conductors affect electrostatics?

Conductors allow for the flow of electric charges, which can affect the distribution of charges and the resulting forces between objects. Conductors also have the ability to shield against electric fields.

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