# Physics

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Hi, i need help on the following questions. Thank you.

1) The potential at location A is 441 V. A positively charged particle is released there from rest and arrives at location B with a speed vB. The potential at location C is 805 V, and when released from rest from this spot, the particle arrives at B with twice the speed it previously had, or 2 vB. Find the potential at B.

2) Four identical charges (+1.6 ìC each) are brought from infinity and fixed to a straight line. Each charge is 0.36 m from the next. Determine the electric potential energy of this group.

3) Identical point charges of +1.7 ìC are fixed to diagonally opposite corners of a square. A third charge is then fixed at the center of the square, such that it causes the potentials at the empty corners to change signs without changing magnitudes. Find the third charge.

Please post questions one at a time.

1). Assume the mass of the particle released from either A or C is the same. Call it M.
(1/2)M vB^2 = 441 - VB
(1/2)M (2vB)^2 = 805 - VB

VB is the potential at point B
805 - VB = 4 (441 - VB)

Solve for VB