(a) When switched on, the trimmer speeds up from 0 to 2 700 rev/min in 0.200 s. What average power is delivered to the head by the trimmer motor while it is accelerating? w (b) When the trimmer is cutting grass, it spins at 1 930 rev/min and the grass exerts an average tangential force of 6.80 N on the outer end of the cord, which is still at a radial distance of 16.0 cm from the outer edge of the spool. What is the power delivered to the head under load? w

(a) When switched on, the trimmer speeds up from 0 to 2 700 rev/min in 0.200 s. What average power is delivered to the head by the trimmer motor while it is accelerating? w (b) When the trimmer is cutting grass, it spins at 1 930 rev/min and the grass exerts an average tangential force of 6.80 N on the outer end of the cord, which is still at a radial distance of 16.0 cm from the outer edge of the spool. What is the power delivered to the head under load? w

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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Concept explainers

Torque

Torque is the rotational equivalent of linear force in physics and mechanics. Based on the course of study, it is also known as the moment of force, rotational force, or turning effect.

Question

The head of a grass string trimmer has 100 g of cord wound in a light, cylindrical spool with inside diameter 3.00 cm and outside diameter 18.0 cm as shown in the figure below. The cord has a linear density of
10.0 g/m. A single strand of the cord extends 16.0 cm from the outer edge of the spool.
-16.0cm
+3.00 cm
18.0 cm
(a) When switched on, the trimmer speeds up from 0 to 2 700 rev/min in 0.200 s. What average power is delivered to the head by the trimmer motor while it is accelerating?
W
(b) When the trimmer is cutting grass, it spins at 1 930 rev/min and the grass exerts an average tangential force of 6.80 N on the outer end of the cord, which is still at a radial distance of 16.0 cm from
the outer edge of the spool. What is the power delivered to the head under load?
W

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