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Book push Forces problem

  • Thread starter vanitymdl
  • Start date
  • #1
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Homework Statement


A 0.407 kg book rests at an angle against one side of a bookshelf. The magnitude and direction of the total force exerted on the book by the left side of the bookshelf are given by:

Force Left = 2.17 Newtons and θ=59 degrees

What must the magnitude and direction of the total force exerted on the book by the bottom of the bookshelf be in order for the book to remain in this position?

Force book = ___?___Newtons
θ = ___?___degrees


Homework Equations





The Attempt at a Solution



Sum of forces in x:

2.17sin(59) - Fcos(θ) = 0 => Fcos(θ) = 1.86

Sum of forces in y

2.17cos(59) + Fsin(θ) = 0 => Fsin(θ) = -1.1176

tan(θ) = (-1.1176)/(1.86) => θ = 211 degrees

F = 2.17 N

this is wrong though
 

Answers and Replies

  • #2
rcgldr
Homework Helper
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The sum of the forces in y must counter the force exerted by gravity, which is m g.
 
  • #3
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So I was in the right track?
I just need to change my formula to 2.17cos(59) + Fsin(θ) = mg
 
  • #4
rcgldr
Homework Helper
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Is the 59 θ the angle from vertical or the angle from horizontal?
 

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