# HELP Finding Initial Separation

• Vettel
In summary, using conservation of energy and momentum, the initial separation between two particles with masses of 3.00 10-3 kg and 6.00 10-3 kg and the same charge of +7.50 µC was found to be 0.0928 m when the separation between them is 0.100 m and the speed of the 3.00 10-3 kg particle is 130 m/s.
Vettel
One particle has a mass of 3.00 10-3 kg and a charge of +7.50 µC. A second particle has a mass of 6.00 10-3 kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation between them is 0.100 m, the speed of the 3.00 10-3 kg particle is 130 m/s. Find the initial separation between the particles.

So, I used conservation of energy and figured out this equation;

kq^2/r = kq^2/d +1/2m1v1 + 1/2m2v2
where r is initial separation and m1 is 3.00e-3 and m2 is 6.00e-3.

By F1=F2, m1a1=m2a2 and I found out that v2 is v1/2. Am I right so far?
Then I solve the equation above for r and I got 0.0928 but it was wrong.
Can anybody help me please? I don't have any clue where I screwed up..

Thanks!

Welcome to PF!

Hi Vettel! Welcome to PF!

(try using the X2 and X2 icons just above the Reply box )
Vettel said:
By F1=F2, m1a1=m2a2 and I found out that v2 is v1/2. Am I right so far?

Yes.

(But conservation of momentum would get you there quicker. )
So, I used conservation of energy and figured out this equation;

kq^2/r = kq^2/d +1/2m1v1 + 1/2m2v2
where r is initial separation and m1 is 3.00e-3 and m2 is 6.00e-3.

oh wow.. what a stupid mistake... no wonder I keep getting the wrong answer! Thank you so much! :)

## 1. What is "HELP Finding Initial Separation"?

"HELP Finding Initial Separation" is a scientific method used to calculate the initial separation between two objects in motion. It is commonly used in fields such as physics and astronomy to determine the distance between objects in space.

## 2. Why is it important to find the initial separation between two objects?

Finding the initial separation between two objects allows scientists to understand the relationship between the objects and the forces acting upon them. This information is crucial in predicting the future motion of the objects and making accurate calculations and predictions.

## 3. How is "HELP Finding Initial Separation" calculated?

The method involves using the initial velocity and acceleration of the objects to determine the initial displacement between them. This can be done using mathematical equations such as the kinematic equations or by graphing the motion and calculating the area under the curve.

## 4. What are some real-world applications of "HELP Finding Initial Separation"?

"HELP Finding Initial Separation" is used in various fields such as engineering, physics, and astronomy. It can be applied to determine the distance between planets, the initial position of a projectile, or the starting point of a moving vehicle.

## 5. Are there any limitations to "HELP Finding Initial Separation"?

Like all scientific methods, "HELP Finding Initial Separation" has its limitations. It assumes that the objects are moving in a straight line with constant acceleration, which may not always be the case in real-world scenarios. Additionally, it does not take into account external factors such as air resistance or friction, which can affect the accuracy of the calculations.

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