Minimizing Friction for a Ball in a Rough Bowl: Accelerations and Velocity

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Homework Help Overview

The problem involves a ball of mass m and radius r released from the edge of a rough bowl, analyzing its tangential and radial accelerations at a given angle θ, as well as determining the minimum friction coefficient required to prevent slipping. The discussion centers around concepts of energy conservation, rotational dynamics, and the forces acting on the ball.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the conservation of energy to relate potential energy to kinetic energy, questioning how to account for both translational and rotational kinetic energy. Some participants raise concerns about the role of friction and whether the ball can roll from the start.

Discussion Status

The discussion is active with various approaches being explored, including energy conservation and the effects of friction. Participants are questioning assumptions about the initial conditions and the nature of motion (sliding vs. rolling) of the ball, indicating a productive examination of the problem without reaching a consensus.

Contextual Notes

There is some confusion regarding the definitions of R and r, as well as the initial conditions of the ball's motion. Participants note the importance of understanding the forces acting on the ball, particularly at the start of its motion.

  • #91
after ##\theta_0## the ball reaches the other side of the bowl, to ##\pi-\theta_0##:
$$\mu_{s}(\pi-\theta_0)=\frac{2\,cos(\pi-\theta_0)}{17\,sin(\pi-\theta_0)-10\,sin\theta_{0}+\frac{7R}{g}\omega_{0}^2}=\frac{-2\cos\theta_0}{7\sin\theta_0+\frac{7R}{g}\omega_0^2}<0$$
Also how do you know that for this particular problem, not in general: ##\mu_{s}^{(max)}\geq \mu_{k}##
We don't know ##\mu_k## and not ##\mu_s## simce we don't know ##\theta_0## and ##\omega_0##
 
Last edited:

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