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3 equal 1.20uC point charges are placed at the corners of an equilateral triangl

ID: 1880950 • Letter: 3

Question

3 equal 1.20uC point charges are placed at the corners of an equilateral triangle whose sides are 0.5m long. (Take U of the system to be 0 when 3 charges are separated by infinite distance)
A) what is the potential energy between any 2 charges in the system
B)What is the potential energy of the entire system
C) if two of the charges are held in place and the 2nd is allowed to move, what will be the speed of the 3rd charge when it has moved to a distance very far from the two other charges 3 equal 1.20uC point charges are placed at the corners of an equilateral triangle whose sides are 0.5m long. (Take U of the system to be 0 when 3 charges are separated by infinite distance) 3 equal 1.20uC point charges are placed at the corners of an equilateral triangle whose sides are 0.5m long. (Take U of the system to be 0 when 3 charges are separated by infinite distance)
A) what is the potential energy between any 2 charges in the system
B)What is the potential energy of the entire system
C) if two of the charges are held in place and the 2nd is allowed to move, what will be the speed of the 3rd charge when it has moved to a distance very far from the two other charges

Explanation / Answer

a) PE of two charges = 2 [ K q1 q2 /r ]

= 2 [ 9 x 109 x 1.2x10-6 x  1.2x10-6 /0.5 ]  

= 0.0518 J

b)  potential energy of the entire system

= 3 [ K q1 q2 /r ]

= 3 [ 9 x 109 x 1.2x10-6 x  1.2x10-6 /0.5 ]  

= 0.0776 J

c) from WPE
ki + pi = Kf + Pf

0 +   0.0776 = 1/2 mv2 + 0.0518

KE = 0.02596 J

if mass would have given put KE = 1/2 mv2

v can be found

answer