---
title: "A small bead of mass \\(m = 0.050\\text{ kg}\\) and positive charge \\(q = +0.020\\text{ C}\\) is constrained to slide without friction along a straight, horizontal insulating wire aligned with the \\(x\\)-axis. In this region, the electric potential as a function of position along the wire is given by \\(V(x) = 125 – 5.0x^2\\), where \\(V\\) is in volts and \\(x\\) is in meters. The bead is released from rest at \\(x = 0\\). What is the speed of the bead when it reaches \\(x = 4.0\\text{ m}\\)?"
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url: "https://nerd-notes.com/ubq/121092/"
date_modified: "2026-08-23T04:57:49+00:00"
---

# A small bead of mass \(m = 0.050\text{ kg}\) and positive charge \(q = +0.020\text{ C}\) is constrained to slide without friction along a straight, horizontal insulating wire aligned with the \(x\)-axis. In this region, the electric potential as a function of position along the wire is given by \(V(x) = 125 – 5.0x^2\), where \(V\) is in volts and \(x\) is in meters. The bead is released from rest at \(x = 0\). What is the speed of the bead when it reaches \(x = 4.0\text{ m}\)?

A small bead of mass \(m = 0.050\text{ kg}\) and positive charge \(q = +0.020\text{ C}\) is constrained to slide without friction along a straight, horizontal insulating wire aligned with the \(x\)-axis. In this region, the electric potential as a function of position along the wire is given by \(V(x) = 125 - 5.0x^2\), where \(V\) is in volts and \(x\) is in meters. The bead is released from rest at \(x = 0\). What is the speed of the bead when it reaches \(x = 4.0\text{ m}\)?

![A horizontal line represents an insulating wire along an axis labeled x. A small solid circle representing a bead is positioned on the wire at a vertical tick mark labeled x = 0. A second vertical tick mark is located to the right on the wire and labeled x = 4.0 m. A horizontal dashed arrow points from the bead toward the right along the wire. A label above the wire reads V(x) = 125 - 5.0x^2. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787461069-hQWf6w.jpg)

- **A.** \(4.0\text{ m/s}\)
- **B.** \(6.0\text{ m/s}\)
- **C.** \(8.0\text{ m/s}\)
- **D.** \(10\text{ m/s}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121092/*