Question
MasteringPhysics: Homework 2a- Google Chrome Secure https//session.masteringphysics.com/myct/itemView?assignmentProblemID-89785663 K Homework 2a Problem 16.36 (EC) Find the speed of the moving charge when it's 1.0 cm from the fixed charge Express your answer to two significant figures and include the appropriate units. View Available Hint(s) Constants 1 Periodic Table Two identical 35 g particles each carry 1.0 C of charge One is held fixed, and the other is placed 10 mm away and released. t-168 Submit Previous Answers × incorrect; Try Again: 4 attempts remaining Part B Find the speed of the moving charge when it's 10 km from the fxed charge Express your answer to two significant figures and include the appropriate units View Available Hint(s) Type here to search
Explanation / Answer
using law of conservation of energy
Total energy at the seperation of 1 mm = Total energy at the seperation of 1.0 cm
K1+U1 = K2+U2
0+(k*q1*q2/r1) = (0.5*m*v^2)+(k*q1*q2/r2)
0+((9*10^9*1*10^-6*1*10^-6)/(1*10^-3)) = (0.5*35*10^-3*v^2)+((9*10^9*1*10^-6*1*10^-6)/(1*10^-2))
v = 21.5 m/s
b) when r2 = 1 km = 1000 m
0+(k*q1*q2/r1) = (0.5*m*v^2)+(k*q1*q2/r2)
0+((9*10^9*1*10^-6*1*10^-6)/(1*10^-3)) = (0.5*35*10^-3*v^2)+((9*10^9*1*10^-6*1*10^-6)/(1000))
v = 22.6 m/sec