1 / 6

Broken Back?

Broken Back?. A smokejumper (mass = 70 kg) hits the ground with 25x body weight. If the load is concentrated on the facet joints, which have an area of 1 cm 2 , will they break ? (F = mass x g; g = 9.81 m/s 2 ) Yes No It depends …. Broken Back?.

duaa
Télécharger la présentation

Broken Back?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Broken Back? A smokejumper (mass = 70 kg) hits the ground with 25x body weight. If the load is concentrated on the facet joints, which have an area of 1 cm2, will they break? (F = mass x g; g = 9.81 m/s2) • Yes • No • It depends …

  2. Broken Back? A smokejumper (mass = 70 kg) hits the ground with 25x body weight. If the load is concentrated on the facet joints, which have an area of 1 cm2, will they break? (F = mass x g; g = 9.81 m/s2) Given: F = 25 x mass x g F = 25 x 70kg x 9.81m/s2 = 17167.5 N A = 1 cm2 Stress=F/A A = (1 cm2)(1 m/100 cm)(1 m/100 cm) A = 0.0001 m2 = 1 x 10-4 m2 Stress = F(N)/A(m2) = 171675000 = 171.675 MPa Bone Ultimate Stress = 190 MPa (Compression) 171.675 MPa < 190 MPa Below limit : NO will not break

  3. Good Vibrations

  4. Good Vibrations Small, subtle vibrations reduce bone loss in laboratory animals.

  5. Good Vibrations Small, subtle vibrations reduce bone loss in laboratory animals.

  6. http://www.marodyne.com/research/

More Related