Suppose that during each step, the leg of the student in Example 14.11 swings through a total distance of 2.0 m. At the end of the swing, this foot rests on the ground for 0.2 s before the other leg begins its swing. a. At what speed does this student walk? (Think carefully about how far forward the student moves at each step.) b. The swinging leg reaches its maximum speed at the bottom of its arc. How many times faster is this maximum leg speed (measured with respect to the ground) than the average walking speed? SEE EX 14.11 in ATTACHED PICTURE Finding the frequency of a swinging leg B10EXAMPLE 14.11A student in a biomechanics lab measures the length of his leg,from hip to heel, to be 0.90 m. What is the frequency of the pen-dulum motion of the student's leg? What is the period?The expression for the frequency is similar to that for the simplependulum, but with an additional numerical factor of 3/2 insidethe square root. The numerical value of the frequency isSTRATEGIZE Equation 14.29 for the period of a physical pen-dulum contains the center-of-gravity distance d and the momentof inertia I. We’ll need to make some simplifying assumptions toestimate these lengths.(9.8 m/s²1f=32V090 m)= 0.64 HzThe period isPREPARE We can model a human leg reasonably well as a rod ofuniform cross section, pivoted at one end (the hip). Recall fromChapter 7 that the moment of inertia of a rod pivoted about itsend is mL?. The center of gravity of a uniform leg is at the mid-point, so d= L/2.1T== 1.6 sASSESS Notice that we didn’t need to know the mass of the legto find the period. The period of a physical pendulum does notSOLVE The frequency of a physical pendulum is given by Equa- depend on the mass, just as it doesn't for the simple pendulum.tion 14.29. Before we put in numbers, we will use symbolic rela-tionships and simplify:The period depends only on the distribution of mass. When youwalk, swinging your free leg forward to take another stride corre-sponds to half a period of this pendulum motion. For a period of1.6 s, this is 0.80 s. For a normal walking pace, one stride in justunder one second sounds about right.1f=|mgdmg(L/2)3 g11I22 L

Name: Suppose that during each step, the leg of the student in Example 14.11
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Description: Suppose that during each step, the leg of the student in Example 14.11 swings through a total distance of 2.0 m. At the end of the swing, this foot rests on the ground for 0.2 s before the other leg begins its swing. a. At what speed does this studen