Circular Motion Video Lessons

Concept

Problem: An ant of mass m clings to the rim of a flywheel of radius r, as shown above. The flywheel rotates clockwise on a horizontal shaft S with constant angular velocity ω. As the wheel rotates, the ant revolves past the stationary points I, II, III, and IV. The ant can adhere to the wheel with a force much greater than its own weight. 1. It will be most difficult for the ant to adhere to the wheel as it revolves past which of the four points? (A) I (B) II (C) III (D) IV (E) It will be equally difficult for the ant to adhere to the wheel at all points. 2. What is the magnitude of the minimum adhesion force necessary for the ant to stay on the flywheel at point III? (A) mg (B) mω2r (C) mω2r2 + mg (D) mω2r – mg  (E) mω2r + mg

FREE Expert Solution

This problem is all about the direction of net force in circular motion.

Newton's second law:

$\overline{){\mathbf{\Sigma }}{\mathbf{F}}{\mathbf{=}}{\mathbf{m}}{\mathbf{a}}}$

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Problem Details

An ant of mass m clings to the rim of a flywheel of radius r, as shown above. The flywheel rotates clockwise on a horizontal shaft S with constant angular velocity ω. As the wheel rotates, the ant revolves past the stationary points I, II, III, and IV. The ant can adhere to the wheel with a force much greater than its own weight.

1. It will be most difficult for the ant to adhere to the wheel as it revolves past which of the four points?

(A) I

(B) II

(C) III

(D) IV

(E) It will be equally difficult for the ant to adhere to the wheel at all points.

2. What is the magnitude of the minimum adhesion force necessary for the ant to stay on the flywheel at point III?

(A) mg

(B) mω2

(C) mω2r2 + mg

(D) mω2r – mg

(E) mω2r + mg