(II) The human leg can be compared to a physical pendulum, with a “natural” swinging period al which walking is easiest. Consider the leg as two rods joined rigidly together at the knee; the axis for the leg is the hip joint. The length of each rod is about the same, 55 cm. The upper rod has a mass of 7.0 kg and the lower rod has a mass of 4.0 kg. ( a ) Calculate the natural swinging period of the system. ( b ) Check your answer by standing on a chair and measuring the time for one or more complete back-and-forth swings. The effect of a shorter leg is a shorter swinging period, enabling a faster “natural” stride.
(II) The human leg can be compared to a physical pendulum, with a “natural” swinging period al which walking is easiest. Consider the leg as two rods joined rigidly together at the knee; the axis for the leg is the hip joint. The length of each rod is about the same, 55 cm. The upper rod has a mass of 7.0 kg and the lower rod has a mass of 4.0 kg. ( a ) Calculate the natural swinging period of the system. ( b ) Check your answer by standing on a chair and measuring the time for one or more complete back-and-forth swings. The effect of a shorter leg is a shorter swinging period, enabling a faster “natural” stride.
(II) The human leg can be compared to a physical pendulum, with a “natural” swinging period al which walking is easiest. Consider the leg as two rods joined rigidly together at the knee; the axis for the leg is the hip joint. The length of each rod is about the same, 55 cm. The upper rod has a mass of 7.0 kg and the lower rod has a mass of 4.0 kg. (a) Calculate the natural swinging period of the system. (b) Check your answer by standing on a chair and measuring the time for one or more complete back-and-forth swings. The effect of a shorter leg is a shorter swinging period, enabling a faster “natural” stride.
(c) A small ball of mass 0.75 kg is attached to one end of a 1.25 m long
massless rod, and the other end of the rod is hung from a pivot.
When the resulting pendulum is 30° from the vertical, what is the
magnitude of the gravitational torque calculated about the pivot?
*12–176. The car travels around the circular track with a
constant speed of 20 m/s. Determine the car's radial and
transverse components of velocity and acceleration at the
instant 0 = 7/4 rad.
12–177. The car travels around the circular track such that
its transverse component is 0 = (0.006/2) rad, where t is in
seconds. Determine the car's radial and transverse
components of velocity and acceleration at the instant t=4 s.
r = (400 cos 0) m
A small ball of mass 0.5 kg is attached to one end of a 1.8-m-long massless rod, and the other end of the rod is hung from a pivot. When the resulting pendulum is 40◦ from the vertical, what is the magnitude of thegravitational torque calculated about the pivot?
Chapter 14 Solutions
Physics for Scientists and Engineers with Modern Physics
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
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