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**1. Homework Statement**

Two protons are held fixed at a distance of 3 angstroms (3 x 10-10 m) from

one another. The protons have a charge of +1.6 x 10-19 C. After they are released they

repel each other and fly apart and each acquires some kinetic energy. What is the final

total kinetic energy of the two particles when they are at a large distance from each other?

**2. Homework Equations**

Potential Electric Energy= (1/4pie)*q1q2/r

Ki+Ui=Kf+Uf

**3. The Attempt at a Solution**

3A * (3e-10m/1 A) = 9e-10m

Ue=(9e9 Nm^2/C^2)(1.6e-19C)(1.6e-19C)/(9e-10m)= 2.56e-19 Nm

And I know that as r goes to infinity, potential energy goes to 0

thus

0+Ui=Kf+0

2.56e-19J=Kf

But the answer is 7.7e-19, what i am doing wrong, what step am I missing thank you!