Electrostatic Net Force Problem

[jlholmes80]

Homework Statement

I am trying to help a friends daughter understand her physics homework. We have been stumped for hours! We don't really understand what her teacher was talking about and what we have figured out has mostly come from google.

The problem is (this is drawn out no real information is given): q2 1.0c directly north of that is q1 2.0c (the line between them shows a distance of 3m) then directly to the east of q2 is 4.0c and the distance between q2 and q3 is 4m. * (EDIT) Calculate net force on q2.

Homework Equations

F=qQ/r^2
K=9x10^9

The Attempt at a Solution

Lots of google searches. The best we can come up with is that you plug in the information for each individual. (ie q1 q2, q1 q3, q2 q3), but if we did that there is nothing in her notes on how to combine them to come up with a net force? so for q1 q2 would be 3.06*10^9. Are we going about this all wrong? Any help would be appreciated.

 

[Delphi51]

Welcome to PF!
The information you gave is clear, except there is no question. What are you trying to calculate? Net force on which charge?

 

[jlholmes80]

Sorry I edited. It says net force on q2.

 

[Delphi51]

Use the equation you wrote to find the force on q2 due to the charge q1.
Then use it again to find the force due to the 4 C charge.
Finally, add the two force vectors. You can do it by drawing arrows on graph paper, or sketching them on plain paper and finding the sum by trigonometry (law of sines and law of cosines) or by splitting the one at an angle into horizontal and vertical components.

 

[asteriatic]

Hello,

I understand your frustration with this problem. It can be challenging to understand new concepts and apply them to problems. Let me try to explain the concept of electrostatic net force and how to approach this problem.

First, it is important to understand that electrostatic force is a force that is exerted between two charged objects. The magnitude of this force is given by the equation F = k * (q1 * q2)/r^2, where k is the Coulomb's constant (9x10^9 Nm^2/C^2), q1 and q2 are the charges of the two objects, and r is the distance between them.

Now, in this problem, we have three charged objects: q1, q2, and q3. The goal is to find the net force on q2, which is the sum of the individual forces exerted on q2 by q1 and q3. To calculate the force exerted by q1 on q2, we use the equation F = k * (q1 * q2)/r^2, where q1 is 2.0 C and r is 3m. Similarly, for the force exerted by q3 on q2, we use the same equation but with q3 as 4.0 C and r as 4m.

Once we have calculated the individual forces, we can use vector addition to find the net force. This means we add the forces together using vector addition rules, taking into account the direction of the forces. In this case, since the force exerted by q1 is directly north of q2, and the force exerted by q3 is directly east of q2, we can use the Pythagorean theorem to find the magnitude of the net force and trigonometry to find the direction.

In summary, to solve this problem, you need to use the equation F = k * (q1 * q2)/r^2 to calculate the forces exerted by q1 and q3 on q2, and then use vector addition to find the net force. I hope this explanation helps you and your friend's daughter understand the concept better. Remember, practice makes perfect, so keep working on problems and don't be afraid to ask for help when needed. Good luck!