# hw5 - force in the erector spinae muscle Assume that the...

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ME 577 – Human Motion Kinetics Homework #5 Due Wednesday, March 9 1. Assume that a 6 foot tall individual has a mass of 100 kg an average density of 1 g/cm 3 . What is his effective radius if you model him as a cylinder? Calculate the force on the vertebral body if the erector spinae muscles are the only ones providing stability. What happens when this individual takes the Giant-Man formula and increases his height to 30 feet? Assume the height, effective radius, and area of the vertebral body scale geometrically. 2a. First, consider a static analysis of an adult picking up a 30 lbs. child and holding the child at arm’s length (approximately 2.5 ft. from the shoulder). Assuming the shoulder lines up with the vertical axis of the spine, and the distance from the vertebral body to the erector spinae muscle is 2 inches behind the spine, calculate the compressive and shear loads on the spine as well as the
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Unformatted text preview: force in the erector spinae muscle. Assume that the head and torso weight 40 lbs. (2 inches in front of the spine) and the two arms weight 10 lbs. 2b. Next, consider that the child does not want to be picked up and is kicking his or her feet. The child’s center of mass moves back and forth as well as up and down according to a sinusoid (amplitude = 1 inch, frequency = 1 Hz). Write out the kinematics (position, velocity, and acceleration) of the system’s center of mass. (5 points). Write out the equations for the shear, compressive, and erector spinae forces. What are they? Will the peak magnitude of those forces increase or decrease compared to the static case? 3. Assume you are wearing a 25 lbs. backpack (all the other parameters are the same as the normal sized human from problem 1). What is the force on the vertebral body if the erector spinae muscles are the only ones providing stability....
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## This document was uploaded on 12/21/2011.

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