Go Back   Physics Help Forum > High School and Pre-University Physics Help > Equilibrium and Elasticity

Equilibrium and Elasticity Equilibrium and Elasticity Physics Help Forum

LinkBack Thread Tools Display Modes
Old Oct 17th 2010, 01:19 AM   #1
Junior Member
Join Date: Oct 2010
Posts: 7
force supplied by vertebrae, minimal strain, center of grav

Please note that the solution to this problem is not being submitted for any credit.

A person working at a drafting board may hold her head as shown in figure 5.45 requiring muscle action to support the head. The 3 major forces acting are shown. Calculate the direction and magnitude of the force supplied by the 5th vertebrae to hold the head stationary assuming it acts along a line through the center of mass as do the weight and muscle force. Is the direction of the 5th vertebrae likely to produce minimal strain in the upper vertebrae?

Really confused here. Perhaps use trig to determine the forces highlighted in red. Then use arctan to determine theta?

Thank you very much.
Attached Thumbnails
force supplied by vertebrae, minimal strain, center of grav-fig_545.jpg  
nmyers77 is offline   Reply With Quote
Old Oct 17th 2010, 02:29 AM   #2
Physics Team
Unknown008's Avatar
Join Date: Jun 2010
Location: Mauritius
Posts: 609
Well, I assume that F_v is the force that the 5th vertebrae exerts...

You can resolve the forces or use Lami's Theorem. But I'll go with resolving the forces first and if you want to know about the Lami's Theorem, I'll post upon your request.

Components acting along the vertical:

50 + 60 sin(33) = F sin(\theta)

Components acting along the horizontal:

60 cos(33) = F cos(\theta)

Two equations, two unknowns. It should be easy to solve for F and theta.

As for the minimal strain, I'm afraid that it goes into biology, more specifically into bones and locomotive system which I'm not familar with.
Jerry (Got my results!)
It is easier to protect your feet with slippers than to cover the earth with carpet.
No one can go back and change a bad beginning; but anyone can start now and create a successful ending.

If a problem can be solved, no need to worry about it. If it cannot be solved what is the use of worrying?
Unknown008 is offline   Reply With Quote

  Physics Help Forum > High School and Pre-University Physics Help > Equilibrium and Elasticity

center, force, grav, minimal, strain, supplied, vertebrae

Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes

Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
I am confused on the concept/definition for center of mass and center of gravity? hongiddong Kinematics and Dynamics 3 Jul 30th 2014 10:36 AM
Center of Gravity and Centrifugal Force XxJxX Advanced Mechanics 6 Mar 30th 2013 06:50 PM
Strain tensor botee Equilibrium and Elasticity 4 Feb 1st 2013 09:11 PM
Maximum strain of steel? exibo177 Equilibrium and Elasticity 2 May 29th 2012 11:32 AM
Sress & Strain Barney Equilibrium and Elasticity 1 Mar 19th 2011 12:19 PM

Facebook Twitter Google+ RSS Feed