Question #daa19

2 Answers
Jun 7, 2017

"Please refer to the description section and check the operations."Please refer to the description section and check the operations.

Explanation:

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  • The forces and their directions are described in figure-1.

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  • We can solve the problem in many ways.
  • In this solution we used the method of dividing the forces into horizontal and vertical components.

"The components of " F_3 " are :"The components of F3 are :
F_("3x")=F_3*cos(30)=50sqrt (3). sqrt(3)/2=(50.3)/2=150/2=75NF3x=F3cos(30)=503.32=50.32=1502=75N

F_("3y")=F_3.sin(30)=50sqrt(3)*1/2=25sqrt(3)N F3y=F3.sin(30)=50312=253N

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"The components of " F_1 " are :"The components of F1 are :

F_("1x")=F_1*cos(0)=100.1=100NF1x=F1cos(0)=100.1=100N

F_("1y")=F_1.sin(0)=100.0=0NF1y=F1.sin(0)=100.0=0N

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"The components of " F_2 " are :"The components of F2 are :
F_("2x")=F_2*cos(30)=100sqrt (3). sqrt(3)/2=(100.3)/2=300/2=150NF2x=F2cos(30)=1003.32=100.32=3002=150N

F_("2y")=-F_2.sin(30)=100sqrt(3)*1/2=-50sqrt(3)N F2y=F2.sin(30)=100312=503N

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  • Figure-5 shows the vector sum of the horizontal components of the forces.

Sigma F_("x")=F_("1x")+F_("2x")+F_("3x")
Sigma F_("x")=100+150+75=325N

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  • Figure-6 shows the vector sum of the vertical components of the forces.

Sigma F_("y")=F_("1y")+F_("2y")+F_("3y")
Sigma F_("y")=0-50sqrt(3)+25sqrt(3)=-25sqrt(3)N

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  • Figure 7 shows the resultant vector and direction.

F_r=sqrt((Sigma F_x)^2+(Sigma F_y)^2)

F_r=sqrt((325)^2+(-sqrt(25))^2)

F_r=sqrt(105625+625)

F_r=325.96N

  • We must specify the angle of the resultant vector.

tan theta=(Sigma F_y) / (Sigma F_x)

tan theta=-(25sqrt(3))/325=-(sqrt(3))/13=-0.13323468

theta=-7.59^o

Jun 7, 2017

The resultant force is =327.9N in the direction =7.6º of the center rope

Explanation:

cos30=sqrt3/2

sin30=1/2

Resolving in thedirection parallel to the 100N force

F_h=100+50sqrt3cos30 +100sqrt3cos30

=100+50sqrt3*sqrt3/2+100sqrt3*sqrt3/2

=100+75+150=325N

Resolving perpendicular to the 100N force

F_p=100sqrt3sin30-50sqrt30sin30

=100sqrt3*1/2-50sqrt3*1/2

=50sqrt3-25sqrt3

=25sqrt3

The resultant force is

F=sqrt(F_h^2+F_p^2)

=sqrt(325^2+(25sqrt3)^2)

=sqrt107500

=327.9N

The direction is

theta=arctan((25sqrt3)/325)

=arctan(sqrt3/13)

=7.6º