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Planck's law ( by the Frequency)

Planck’s law describes the electromagnetic radiation emitted from a black body at a certain temperature. Radiance and spectral radiance are measures ... more

Planck's law ( by wavelength)

Planck’s law describes the electromagnetic radiation emitted from a black body at a certain temperature. Radiance and spectral radiance are measures ... more

Near depth of field

In optics, particularly as it relates to film and photography, depth of field (DOF) is the distance between the nearest and ... more

Far depth of field

In optics, particularly as it relates to film and photography, depth of field (DOF) is the distance between the nearest and ... more

Worksheet 316

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.

Strategy

The force is equal to the weight supported:

Force (Newton's second law)

and the cross-sectional area of the upper leg bone(femur) is:

Disk area

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:

Young's Modulus

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/

Specific absorption rate - with Current density

Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the human body when exposed to a radio ... more

Lateral earth active pressure (Rankine theory)

Lateral earth pressure is the pressure that soil exerts in the horizontal direction. Rankine’s theory, is a stress field solution that predicts ... more

Effective Radius of a Contact Area between two spheres

Contact mechanics is the study of the deformation of solids that touch each other at one or more points. Hertzian contact stress refers to the localized ... more

Bradley model of the force applied on a contact area between two spheres

Contact mechanics is the study of the deformation of solids that touch each other at one or more points. When two solid surfaces are brought into close ... more

Specific absorption rate - with Increase of temperature

Specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the human body when exposed to a radio ... more

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