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A logistic function or logistic curve is a common “S” shape (sigmoid curve). Data that follows an increasing logistic curve usually describes ... more
A trajectory or flight path is the path that a moving object follows through space as a function of time. A trajectory can be described mathematically ... more
The depth of focus (or depth of field) is a lens optics concept that measures the tolerance of placement of the image plane (the film plane in a camera) in ... more
A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part to transmit torque, in most cases with teeth ... more
Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves.Compared to the emitted ... more
Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves. Compared to the emitted ... more
Converging lens in air will focus a collimated beam travelling along the lens axis to a spot (known as the focal point) at a distance “f” from ... more
Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves. Compared to the emitted ... more
Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves.Compared to the emitted ... more
Strategy
The force is equal to the weight supported:
and the cross-sectional area of the upper leg bone(femur) is:
To find the change in length we use the Young’s modulus formula. The Young’s modulus reference value for a bone under compression is known to be 9×109 N/m2. Now,all quantities except ΔL are known. Thus:
Discussion
This small change in length seems reasonable, consistent with our experience that bones are rigid. In fact, even the rather large forces encountered during strenuous physical activity do not compress or bend bones by large amounts. Although bone is rigid compared with fat or muscle, several of the substances listed in Table 5.3(see reference below) have larger values of Young’s modulus Y . In other words, they are more rigid.
Reference:
This worksheet is a modified version of Example 5.4 page 188 found in :
OpenStax College,College Physics. OpenStax College. 21 June 2012.
http://openstaxcollege.org/textbooks/college-physics
Creative Commons License : http://creativecommons.org/licenses/by/3.0/
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Calculate the change in length of the upper leg bone (the femur) when a 70.0 kg man supports 62.0 kg of his mass on it, assuming the bone to be equivalent to a uniform rod that is 45.0 cm long and 2.00 cm in radius.