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title: "Two gliders of masses \\(m_1\\) and \\(m_2\\) move along a horizontal, frictionless air track with constant velocities such that the velocity of their center of mass in the laboratory frame is \\(v_{\\text{cm}} > 0\\). An observer moves along the track at a constant velocity \\(u\\) relative to the laboratory frame, where \\(0 \\le u \\le v_{\\text{cm}}\\). As the observer’s velocity \\(u\\) increases from \\(0\\) to \\(v_{\\text{cm}}\\), how do the magnitude of the total linear momentum of the two-glider system, the relative speed between the two gliders, and the total kinetic energy of the system, all measured in the observer’s reference frame, change?"
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url: "https://nerd-notes.com/ubq/124159/"
date_modified: "2026-09-28T13:30:48+00:00"
---

# Two gliders of masses \(m_1\) and \(m_2\) move along a horizontal, frictionless air track with constant velocities such that the velocity of their center of mass in the laboratory frame is \(v_{\text{cm}} > 0\). An observer moves along the track at a constant velocity \(u\) relative to the laboratory frame, where \(0 \le u \le v_{\text{cm}}\). As the observer’s velocity \(u\) increases from \(0\) to \(v_{\text{cm}}\), how do the magnitude of the total linear momentum of the two-glider system, the relative speed between the two gliders, and the total kinetic energy of the system, all measured in the observer’s reference frame, change?

Two gliders of masses \(m_1\) and \(m_2\) move along a horizontal, frictionless air track with constant velocities such that the velocity of their center of mass in the laboratory frame is \(v_{\text{cm}} > 0\). An observer moves along the track at a constant velocity \(u\) relative to the laboratory frame, where \(0 \le u \le v_{\text{cm}}\). As the observer's velocity \(u\) increases from \(0\) to \(v_{\text{cm}}\), how do the magnitude of the total linear momentum of the two-glider system, the relative speed between the two gliders, and the total kinetic energy of the system, all measured in the observer's reference frame, change?

- **A.** Total momentum magnitude: Decreases | Relative speed: Remains the same | Total kinetic energy: Decreases
- **B.** Total momentum magnitude: Decreases | Relative speed: Decreases | Total kinetic energy: Decreases
- **C.** Total momentum magnitude: Decreases | Relative speed: Remains the same | Total kinetic energy: Remains the same
- **D.** Total momentum magnitude: Remains the same | Relative speed: Remains the same | Total kinetic energy: Decreases

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/124159/*