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. 90. Upon reducing her speed back down to 5 m/s, she hits a headwind of 5 m/s. How much power is she expending now? A. 100 w B. 200 W C. 500 W D. 1000 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. 90. Upon reducing her speed back down to 5 m/s, she hits a headwind of 5 m/s. How much power is she expending now? A. 100 w B. 200 W C. 500 W D. 1000 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.
90. Upon reducing her speed back down to 5 m/s, she hits a headwind of 5 m/s. How much power is she expending now?
Which of the following best describes how to calculate the average acceleration of
any object?
Average acceleration is always halfway between the initial acceleration of an
object and its final acceleration.
Average acceleration is always equal to the change in velocity of an object
divided by the time interval.
Average acceleration is always equal to the displacement of an object divided by
the time interval.
Average acceleration is always equal to the change in speed of an object divided
by the time interval.
The figure shows the velocity versus time graph for a car driving on a straight road.
Which of the following best describes the acceleration of the car?
v (m/s)
t(s)
The acceleration of the car is negative and decreasing.
The acceleration of the car is constant.
The acceleration of the car is positive and increasing.
The acceleration of the car is positive and decreasing.
The acceleration of the car is negative and increasing.
Which figure could represent the velocity versus time graph of a motorcycle
whose speed is increasing?
v (m/s)
v (m/s)
t(s)
t(s)
Chapter 10 Solutions
Student Workbook for College Physics: A Strategic Approach Volume 1 (Chs. 1-16)
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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