Question regarding Coulomb's Law

In summary, the homework statement has three spheres next to each other with different charges. The one on the left has a positive charge of +25.5μ C. The one on the right has a negative charge of -25.5μ C. The sphere in the middle has a charge of +2.5μ C. The force on the first sphere is 73.14 N. The force on the second sphere is 36.7 N. The force on the third sphere is 0.
  • #1
Keshav Santhanam
5
0

Homework Statement


Three separate spheres next to each other. The one on the left is positive (charge of +25.5μ C). The one on the right is negative(-25.5μ C). The two are separated by 0.25m. The third sphere has a charge of +2.5μ C and is placed exactly halfway between the two. Find the force on the first, second, and third object(with direction, of course). (To clarify, the problem is asking for the total force on the first object (from the other two), etc.)

Homework Equations


Coulomb's law

The Attempt at a Solution


I successfully found the charge between the spheres on the left and right (completely disregarding the third one in the middle). That gave me 93.6 N.

That's about it because I can't seem to visualize the movement of all three objects. Help would be appreciated!

EDIT: I have the answers, just forgot to add them in here:
73.14 N is the force on the middle object (rightward)
The leftmost sphere: 56.92 N right
The rightmost sphere: 36.7 N right
 
Last edited:
Physics news on Phys.org
  • #2
Keshav Santhanam said:
I successfully found the charge between the spheres on the left and right (completely disregarding the third one in the middle). That gave me 93.6 N.
Can you show us how you did that? I'm curious because there's no mention in the problem statement of the distances between the spheres :wink:
 
  • #3
gneill said:
Can you show us how you did that? I'm curious because there's no mention in the problem statement of the distances between the spheres :wink:
Well, I had to screw something up on my first post :oldfrown:
I will add it in now.
 
  • #4
Okay, so have you drawn a sketch of the layout and penciled in the distances between the centers of all the spheres?

Keshav Santhanam said:
That's about it because I can't seem to visualize the movement of all three objects. Help would be appreciated!
I think you need to assume that all the spheres are fixed in place, so that there's no movement involved.
 
  • #5
gneill said:
Okay, so have you drawn a sketch of the layout and penciled in the distances between the centers of all the spheres? I think you need to assume that all the spheres are fixed in place, so that there's no movement involved.
I think I see where you are coming from. Would the sphere the force is acting upon be free to move? Or none at all? The directions didn't specify.
 
  • #6
Keshav Santhanam said:
I think I see where you are coming from. Would the sphere the force is acting upon be free to move? Or none at all? The directions didn't specify.
Presume that they are not free to move. They are fixed in place.
 
  • #7
gneill said:
Presume that they are not free to move. They are fixed in place.
I think if they were free to move the forces between them would continuously change (because the force is proportional to distance squared). So, them being stationary makes sense, but I recall my teacher stating that in each part of the problem a different sphere was free to move.
If we assume they are fixed, how would I set up this problem? Should I cancel the forces of either sphere (the ones on the ends) while solving for the one in the middle, etc?
 
  • #8
Keshav Santhanam said:
So, them being stationary makes sense, but I recall my teacher stating that in each part of the problem a different sphere was free to move.
Without seeing the problem in full, I can only surmise that they will be looking for initial accelerations or something similar (assuming that the spheres have mass values).

Keshav Santhanam said:
If we assume they are fixed, how would I set up this problem? Should I cancel the forces of either sphere (the ones on the ends) while solving for the one in the middle, etc?
Yes. Forces are vectors and add as such.
 
  • #9
gneill said:
Without seeing the problem in full, I can only surmise that they will be looking for initial accelerations or something similar (assuming that the spheres have mass values).Yes. Forces are vectors and add as such.
I think I might just have to ask my teacher about this one. That was all the information given. Thanks for the help though, I appreciate it!
 

What is Coulomb's Law?

Coulomb's Law is a fundamental law of physics that describes the relationship between the electric force between two charged particles and the distance between them. It states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Who discovered Coulomb's Law?

Coulomb's Law was discovered by French physicist Charles-Augustin de Coulomb in 1785. He conducted experiments with charged particles and found that the force between them followed a specific mathematical relationship.

What is the equation for Coulomb's Law?

The equation for Coulomb's Law is F = k(q1q2)/r^2, where F is the force between two charged particles, k is the Coulomb constant (8.99 x 10^9 Nm^2/C^2), q1 and q2 are the charges of the particles, and r is the distance between them.

What are the SI units for Coulomb's Law?

The SI units for Coulomb's Law are newtons (force), meters (distance), and coulombs (charge). The Coulomb constant, k, has units of newton-meter squared per coulomb squared.

How is Coulomb's Law related to electric fields?

Coulomb's Law is closely related to electric fields. Electric fields are created by charged particles and are responsible for the force experienced by other charged particles in their vicinity. The electric field strength is directly proportional to the force experienced by a test charge, and the direction of the electric field is the same as the direction of the force experienced by the test charge.

Similar threads

Replies
22
Views
1K
  • Special and General Relativity
Replies
24
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Classical Physics
Replies
17
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
788
  • Introductory Physics Homework Help
Replies
12
Views
4K
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
Back
Top