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Speed of Sound in Plasma

The speed of sound is the distance travelled per unit of time by a sound wave propagating through an elastic medium.
The speed of sound in a plasma ... more

Doppler Effect Wavelength Front

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 Wavelength Behind

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

Rotational stiffness ( depended on rigidity modulus of the material)

Stiffness is the rigidity of an object — the extent to which it resists deformation in response to an applied force. In general, stiffness is not the same ... more

Doppler Effect Approaching Receiver

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 Receding Receiver

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

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/

Shear modulus (related to Young's modulus and Poisson's ratio)

The shear modulus is one of several quantities for measuring the stiffness of materials and describes the material’s response to shear stress (like ... more

Friction velocity (shear velocity)

Friction velocity, is a form by which a shear stress may be re-written in units of velocity. It is useful as a method in fluid mechanics to compare true ... more

Drift Velocity

The drift velocity is the average velocity that a particle, such as an electron, attains in a material due to an electric field. It can also be referred to ... more

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