Two protons moving toward each other

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In summary, the conversation discusses a physics homework problem involving two protons with an initial kinetic energy of 0.16 MeV each, and the question asks for the separation between the protons when they come to a stop. One approach is to set the initial kinetic energy equal to the final potential energy and solve for the distance, but this method can lead to incorrect answers if the initial energy is not divided evenly between the two protons. The correct approach is to consider the total initial kinetic energy of both protons (0.32 MeV) and use this value in the equation for electric potential energy to solve for the distance. One person in the conversation made a mistake by only considering the kinetic energy of one proton, but this was
  • #1
rkjul
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Homework Statement



Two protons that are very far apart are hurled straight at each other, each with an initial kinetic energy of 0.16 MeV, where 1 mega electron volt is equal to 10^6*(1.6*10^-19) joules. What is the separation of the protons from each other when they momentarily come to a stop?


Homework Equations



E=mc^2+K+U
U,electric=(1/4 pi epsilon)*(q1q2/r)

The Attempt at a Solution



I've been trying to figure this one out for about a half hour. I tried finding the potential energy U by rearranging terms in the equation for E. I then took that number and set it equal to (1/4 pi epsilon)*(q1q2/r)) and tried to find r (the distance) that way, but my answer was wrong. Any ideas?
 
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  • #2
I can't work out what you did but if you set the initial kinetic energy equal to the final potential energy, it's trivial, surely ?
 
  • #3
Mentz114 said:
I can't work out what you did but if you set the initial kinetic energy equal to the final potential energy, it's trivial, surely ?


Thanks...that's what I did. I took that number and then used that in the equation for electric potential energy to obtain the distance.

Sometimes I have a habit of making silly mistakes/overthinking things.
 
  • #4
rkjul said:

The Attempt at a Solution



I've been trying to figure this one out for about a half hour. I tried finding the potential energy U by rearranging terms in the equation for E. I then took that number and set it equal to (1/4 pi epsilon)*(q1q2/r)) and tried to find r (the distance) that way, but my answer was wrong. Any ideas?

Your description is a bit nebulous. Could you please show your numerical calculations? What result have you been getting?
 
  • #5
I am attempting to solve this problem. It seems simple enough but I seem to be getting the wrong answer.

Here is what I have done:
Uf=Ki

9e9*(1.6e-19)2
--------------------- = (.16)(1e6)(1.6e-19)
r

2.304e-28 = 2.56e-14*r
r=9.0e-15

Can someone help me figure out where I went wrong?
 
  • #6
Remember your initial energy is 2*(0.16 MeV), since both protons are moving.
 
  • #7
That was the problem. Thank you very much.
 
  • #8
I have this same homework question (but my Ki is .21MeV). Can someone explain it to me in detail? I'm trying to make sure I understand why it's done this way.
 

1. What happens when two protons move toward each other?

When two protons move toward each other, they are attracted to each other due to their opposite electrical charges. This attraction is known as the electromagnetic force.

2. How do two protons move toward each other?

Two protons can move toward each other through the force of gravity or through the electromagnetic force. Gravity is a much weaker force compared to the electromagnetic force, so it would only have a noticeable effect at very large distances.

3. What is the role of the strong nuclear force in two protons moving toward each other?

The strong nuclear force is responsible for holding the two protons together in the nucleus of an atom. It is the strongest of the four fundamental forces and is what keeps the positively charged protons from repelling each other.

4. Can two protons collide with each other?

Yes, two protons can collide with each other if they have enough energy. This can happen in high-energy particle accelerators, such as the Large Hadron Collider, where protons are accelerated to very high speeds and collide with each other, producing new particles.

5. What happens when two protons collide?

When two protons collide, they release a tremendous amount of energy. This energy can be converted into new particles, such as protons, neutrons, or other subatomic particles. It can also result in the production of high-energy radiation, such as gamma rays.

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