---
title: "Two identical blocks, each of mass \\(m\\), are connected by an ideal spring and rest on a frictionless horizontal floor. A constant horizontal force of magnitude \\(F\\) is applied to the right block, pulling it toward the right. At a particular instant, the left and right blocks move to the right with speeds \\(v_1\\) and \\(v_2\\), respectively, where \\(v_2 > v_1\\). Which of the following expressions represents the instantaneous rate of change of the internal energy of the two-block-spring system?"
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url: "https://nerd-notes.com/ubq/124005/"
date_modified: "2026-09-28T13:30:09+00:00"
---

# Two identical blocks, each of mass \(m\), are connected by an ideal spring and rest on a frictionless horizontal floor. A constant horizontal force of magnitude \(F\) is applied to the right block, pulling it toward the right. At a particular instant, the left and right blocks move to the right with speeds \(v_1\) and \(v_2\), respectively, where \(v_2 > v_1\). Which of the following expressions represents the instantaneous rate of change of the internal energy of the two-block-spring system?

Two identical blocks, each of mass \(m\), are connected by an ideal spring and rest on a frictionless horizontal floor. A constant horizontal force of magnitude \(F\) is applied to the right block, pulling it toward the right. At a particular instant, the left and right blocks move to the right with speeds \(v_1\) and \(v_2\), respectively, where \(v_2 > v_1\). Which of the following expressions represents the instantaneous rate of change of the internal energy of the two-block-spring system?

![A horizontal straight line at the bottom represents a frictionless surface. Resting on the surface are two identical square blocks, each labeled m, connected by a horizontal coiled line representing a spring. The left block has a horizontal arrow above it pointing to the right labeled v_1. The right block has a horizontal arrow above it pointing to the right labeled v_2, where the arrow for v_2 is longer than the arrow for v_1. A horizontal arrow originates from the right vertical edge of the right block, points to the right, and is labeled F. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790602209-2BodD0.jpg)

- **A.** \(\dfrac{1}{2} F (v_2 - v_1)\)
- **B.** \(\dfrac{1}{2} F (v_1 + v_2)\)
- **C.** \(F (v_2 - v_1)\)
- **D.** \(F v_2\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/124005/*