---
title: "A cart of mass \\(M\\) carries a small block of mass \\(m\\) as it travels through a vertical circular loop of radius \\(R\\). At the instant the cart is at the top of the loop, it is moving with the minimum speed required for the block to maintain contact with the floor of the cart. What is the magnitude of the net force on the cart-block system at this instant?"
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url: "https://nerd-notes.com/ubq/112698/"
date_modified: "2026-04-30T20:51:12+00:00"
---

# A cart of mass \(M\) carries a small block of mass \(m\) as it travels through a vertical circular loop of radius \(R\). At the instant the cart is at the top of the loop, it is moving with the minimum speed required for the block to maintain contact with the floor of the cart. What is the magnitude of the net force on the cart-block system at this instant?

A cart of mass \(M\) carries a small block of mass \(m\) as it travels through a vertical circular loop of radius \(R\). At the instant the cart is at the top of the loop, it is moving with the minimum speed required for the block to maintain contact with the floor of the cart. What is the magnitude of the net force on the cart-block system at this instant?

![A side view of a circular track of radius R. A small cart of mass M is shown at the very top of the track, upside down. Inside the cart, a small rectangular block of mass m is resting against the floor of the cart (which is currently the ceiling of the cart's interior). An arrow labeled v points horizontally to the left from the cart. A dashed vertical line indicates the radius R from the center of the circle to the top.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1777582271-1lXyPn.jpg)

- **A.** \(mg\)
- **B.** \(Mg\)
- **C.** \((M + m)g\)
- **D.** \(2(M + m)g\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/112698/*