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Ch 22: Electric Charges and Forces
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 22, Problema 49b

A +2.0 nC charge is at the origin and a −4.0 nC charge is at x = 1.0 cm. Would the net force be zero for an electron placed at the same position? Explain.

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Step 1: Begin by recalling Coulomb's Law, which describes the force between two charges. The formula is: F=kqQr2, where k is Coulomb's constant, q and Q are the charges, and r is the distance between them.
Step 2: Consider the electron placed at the same position as the −4.0 nC charge (x = 1.0 cm). The electron will experience forces due to both the +2.0 nC charge at the origin and the −4.0 nC charge at x = 1.0 cm.
Step 3: Analyze the direction of the forces. The electron has a negative charge, so it will be attracted to the positive +2.0 nC charge at the origin and repelled by the negative −4.0 nC charge at x = 1.0 cm. These forces act in opposite directions along the x-axis.
Step 4: Calculate the magnitudes of the forces using Coulomb's Law for each interaction. For the force due to the +2.0 nC charge, use the distance of 1.0 cm (converted to meters). For the force due to the −4.0 nC charge, the distance is effectively zero since the electron is at the same position as the −4.0 nC charge.
Step 5: Conclude that the net force cannot be zero because the force due to the −4.0 nC charge is undefined at zero distance (it approaches infinity), and the force due to the +2.0 nC charge is finite. Therefore, the electron would experience a net force and the system would not be in equilibrium.

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