Results 1 to 7 of 7

Math Help - Physics -equilibrium

  1. #1
    Member
    Joined
    Jan 2009
    Posts
    197

    Exclamation Physics -equilibrium

    How to solve this problem ?
    Physics -equilibrium-geng02-002.jpg

    Please answer in steps
    Thank you
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello mj.alawami
    Quote Originally Posted by mj.alawami View Post
    How to solve this problem ?
    Click image for larger version. 

Name:	geng02 002.jpg 
Views:	83 
Size:	190.1 KB 
ID:	15529

    Please answer in steps
    Thank you
    The beam is 8 m in length; it is uniform. So its weight acts 4 m from each end.

    If the reaction forces at A and B are R_A and R_B kg-wt respectively, take moments about A:
    450 \times 4 + 220\times 5.6 -8R_B=0
    Solve this equation for R_B.

    Then resolve vertically (or take moments about B) to find R_A.

    Can you complete it now?

    Grandad
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jan 2009
    Posts
    197
    Quote Originally Posted by Grandad View Post
    Hello mj.alawamiThe beam is 8 m in length; it is uniform. So its weight acts 4 m from each end.

    If the reaction forces at A and B are R_A and R_B kg-wt respectively, take moments about A:
    450 \times 4 + 220\times 5.6 -8R_B=0
    Solve this equation for R_B.

    Then resolve vertically (or take moments about B) to find R_A.



    Can you complete it now?

    Grandad

    So is the answer RB=379N , and should i take into consideration the gravitational attraction or no?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,698
    Thanks
    454
    Quote Originally Posted by mj.alawami View Post
    So is the answer RB=379N , and should i take into consideration the gravitational attraction or no?
    R_B = 379g \, N
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello mj.alawami
    Quote Originally Posted by mj.alawami View Post
    So is the answer RB=379N , and should i take into consideration the gravitational attraction or no?
    If you are using Newtons as the unit of force, then, yes: multiply by g\; (\approx 9.8), as skeeter has shown you. I was perhaps unwise to suggest a different unit (kg-wt or kg-force).

    Grandad
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Jan 2009
    Posts
    197

    Exclamation

    Quote Originally Posted by Grandad View Post
    Hello mj.alawamiIf you are using Newtons as the unit of force, then, yes: multiply by g\; (\approx 9.8), as skeeter has shown you. I was perhaps unwise to suggest a different unit (kg-wt or kg-force).

    Grandad

    Will Ra and Rb have the same answer ?
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello mj.alawami
    Quote Originally Posted by mj.alawami View Post
    Will Ra and Rb have the same answer ?
    No. Let me re-phrase my first post, take the sum of the vertical forces and equate to zero:
    450g+220g -R_A - R_B = 0
    (Some people denote this by \sum F_y=0.)

    Substitute the value we've found for R_B and solve for R_A.

    Grandad
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Got a physics question or interested in physics?
    Posted in the Math Topics Forum
    Replies: 16
    Last Post: February 3rd 2014, 01:56 AM
  2. Equilibrium physics help!
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: November 27th 2009, 08:06 PM
  3. Physics - Equilibrium in two dimensions
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: June 28th 2009, 02:11 AM
  4. how do solve quantum physics or physics equations
    Posted in the Advanced Applied Math Forum
    Replies: 2
    Last Post: March 26th 2008, 04:33 AM
  5. physics, acceleration, physics problem
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: September 29th 2007, 03:50 AM

Search Tags


/mathhelpforum @mathhelpforum