Work and Power in Cycling When you ride a bicycle at constant speed, almost all of the energy you expend goes into the work you do against the drag force of the air. In this problem, assume that all of the energy expended goes into working against drag. As we saw in Section 5.7, the drag force on an object is approximately proportional to the square of its speed with respect to the air. For this problem, assume that F α v 2 exactly and that the air is motionless with respect to the ground unless noted otherwise. Suppose a cyclist and her bicycle have a combined mass of 60 kg and she is cycling along at a speed of 5 m/s. 87. Under these conditions, how much power does she expend as she cycles? A. 10 W B. 50 W C. 100 W D. 200 W
Work and Power in Cycling When you ride a bicycle at constant speed, almost all of the energy you expend goes into the work you do against the drag force of the air. In this problem, assume that all of the energy expended goes into working against drag. As we saw in Section 5.7, the drag force on an object is approximately proportional to the square of its speed with respect to the air. For this problem, assume that F α v 2 exactly and that the air is motionless with respect to the ground unless noted otherwise. Suppose a cyclist and her bicycle have a combined mass of 60 kg and she is cycling along at a speed of 5 m/s. 87. Under these conditions, how much power does she expend as she cycles? A. 10 W B. 50 W C. 100 W D. 200 W
When you ride a bicycle at constant speed, almost all of the energy you expend goes into the work you do against the drag force of the air. In this problem, assume that all of the energy expended goes into working against drag. As we saw in Section 5.7, the drag force on an object is approximately proportional to the square of its speed with respect to the air. For this problem, assume that F α v2 exactly and that the air is motionless with respect to the ground unless noted otherwise. Suppose a cyclist and her bicycle have a combined mass of 60 kg and she is cycling along at a speed of 5 m/s.
87. Under these conditions, how much power does she expend as she cycles?
At point A, 3.20 m from a small source of sound that is emitting uniformly in all directions, the intensity level is 58.0 dB. What is the intensity of the sound at A? How far from the source must you go so that the intensity is one-fourth of what it was at A? How far must you go so that the sound level is one-fourth of what it was at A?
Make a plot of the acceleration of a ball that is thrown upward at 20 m/s subject to gravitation alone (no drag). Assume upward is the +y direction (and downward negative y).
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8.01x - Lect 11 - Work, Kinetic & Potential Energy, Gravitation, Conservative Forces; Author: Lectures by Walter Lewin. They will make you ♥ Physics.;https://www.youtube.com/watch?v=9gUdDM6LZGo;License: Standard YouTube License, CC-BY