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**1. Consider a long charged straight wire that lies fixed and a particle of charge +2e and mass 6.70E-27 kg. When the particle is at a distance 1.61 cm from the wire it has a speed 2.20E+5 m/s, going away from the wire. When it is at a new distance of 4.01 cm, its speed is 4.00E+6 m/s.**

**2. What is the charge density of the wire?**

**3. I attempted to do this question but had no idea how would I approach this, I thought:**

1) I find total KE by using 1/2(mv^2+mv'^2), and this KE is equivalent to the -U of the system,

2)I know that dU=Q*dV

3) dV= - (integral) E*ds, but I'm not sure which distance I should use.

4)I know that E=lambda/(2pi*r*e0)

Then I have no idea how should I interconnect my information, and I'm confused if about the change in KE and U, and the actualy KE and U. Also, if we are supposed to integrate this, I don't know how to define the upper and lower limit for the function.

Can anyone please help me? I'm really confused on how to do this question.

1) I find total KE by using 1/2(mv^2+mv'^2), and this KE is equivalent to the -U of the system,

2)I know that dU=Q*dV

3) dV= - (integral) E*ds, but I'm not sure which distance I should use.

4)I know that E=lambda/(2pi*r*e0)

Then I have no idea how should I interconnect my information, and I'm confused if about the change in KE and U, and the actualy KE and U. Also, if we are supposed to integrate this, I don't know how to define the upper and lower limit for the function.

Can anyone please help me? I'm really confused on how to do this question.

Thank you very much in advance!