Question
when you bend over a series of large muscles the erector spinae, pull on your spine to hold you up. shows a simplified model of the
parta, what is the tension in the erector muscle?
b.)a force front he pelvic girdle acts on the base of the spine. what is the component of this force in the direction of the spine?(the large force is the cause of many injuries).hint align your said with the axis of the spine.
File Edit View History Bookmarks Tools Window Help mastering in physics-Y·M / MasteringPhysics i : x ps:j MasteringPhysics: Homework #10 i a https://session. masteringphysics.com/myct/itemview?assignmentProblemiDz87358928 o Firefox has prevented the outdated plugin "Adobe Flash" from running on https://session.masteringphysics.com Homework #10Problem 8.47-MC rials When you bend over. a series of large muscles, the erector spinae, pull on your spine to hold you up. Part A Figure 1) shows a simplified model of the spine as a rod of length , that prvots at its lower end In this model, the center of gravity of the 360 N weight of the upper torso is at the center of the spine. The 170 N weight of the head and arms acts at the top of the What is the tension in the erector muscle? Express your answer using four significant figures and inelue * Hints The erector spinae muscles are modeled as a single muscle that acts at an 12" angle to the spine Suppose the person in (Eigure 1) bends over to an O of 1 T62.8 N Effactive location Incorrect: Try Again Part B A forco from the pamc girdle acts on the base of the spine. What a the co in the drectlon of the spine large force la the cause of many backi yaur z aks with the anhre Express your answer using three significant figures and Include the Hintz MacBook Pro 4 2
Explanation / Answer
Torque summation around pivot:
170*L*cos30º 360*(½L)*cos30º - F*(L)*sin12º = 0
F*()*sin12º = [170 + 360*(½)]*cos30º
F = 350*cos30º/[()*sin12º] = 2.187*10^3 N
Note: To solve part B we need more info so am assuming as 1900 N
The force along the length of the spine is the sum of force components along the spine from the three forces
360*sin30º + 170*sin30º + 1900*cos12º = 2.123*10^3 N
