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Dragging a Board problem, fairly simple yet somehow I am getting it wrong?

  • Thread starter jcfor3ver
  • Start date
  • #1
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0

Homework Statement



A uniform board of length and mass lies near a boundary that separates two regions. In region 1, the coefficient of kinetic friction between the board and the surface is , and in region 2, the coefficient is . The positive direction is shown in the figure.



Homework Equations



Wnet= -[(M*g*mu1*L)+(M*g*mu2*L)]



The Attempt at a Solution





^^^^^^ wouldn't that be my solution above? computer is teling me that I am wrong.
 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
10
Initially the board is in μ1 territory and it gets pulled into μ2 territory, right?
Is it stretched out perpendicular to the boundary?
If so, initially the force of friction is mg*μ1. After pulling the full length of the board, the force of friction is mg*μ2. So the work should be somewhere between mg*μ1*L and mg*μ2*L.

I would suggest sketching a graph of force vs distance. The area under this graph will be the work done.
 
  • #3
supratim1
Gold Member
279
1
where is the figure?
 

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