
#1
Mar1308, 02:41 PM

P: 17

1. The problem statement, all variables and given/known data
Velocity of an electron that falls to r from infinity? An electron falls from infinity to r=10^8m from a charge q1=4.8x10^19C. What is the velocity of the electron? 2. Relevant equations U=q1V V=kq2/r 3. The attempt at a solution Potential energy change U. coulomb's constant k=9x10^9, electron charge q2=1.602x10^19C, electron mass m=9.11x10^31kg, kinetic energy Ek=½mv² U=k(q1)(q2)/r=6.912x10^21J set U=Ek => v=(2U/m)^0.5=1.23x10^5m/s Anyone see where I went wrong? Thanks. 


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