The picture shows a cement bag of weight Fg hanging from a rope which itself is supported by two other ropes attached to a ceiling. The latter two ropes make an angle θ1 and θ2 with the ceiling. Determine the tension in each rope. Use the angle addition identity to simplify your result: sin(α ± β) = sin α cos β ± cos α sin β

Answer :

Answer:

[tex]T_1= \dfrac{F_gcos \theta_2}{sin (\theta_1+\theta_2)}[/tex]

Step-by-step explanation:

From the free body diagram attached  below; we will see that

T₃ = Fg   ------ (1)

Thus; as the system is in equilibrium, the net force in the x and y direction shows to be zero

Then;

[tex]\sum F_x= 0 \to T_2 Cos \theta _2 - T_1 cos \theta _1[/tex]

[tex]T_2 Cos \theta _2 = T_1 cos \theta _1 \ \ \ \ \ - - - (2)[/tex]

Also;

[tex]\sum F_y =0 \to T_2sin \theta_2+T_1sin \theta_1 - T_3 = 0[/tex]

[tex]T_3 = T_2sin \theta_2+T_1sin \theta_1[/tex]   ---- (3)

From equation (2):

[tex]T_2 = \dfrac{T_1cos \theta_1}{cos \theta_2}[/tex]

Replacing the above value for  T₂  into equation 3; we have

[tex]T_3 = \dfrac{T_1cos \theta_1}{cos \theta_2}sin \theta_2+T_1sin \theta_1[/tex]

[tex]T_3 cos \theta_2 = {T_1cos \theta_1}{}sin \theta_2+T_1sin \theta_1 cos \theta_2[/tex]

[tex]T_3 cos \theta_2 = T_1(cos \theta_1 sin \theta_2+sin \theta_1 cos \theta_2)[/tex]  ---- (4)

Using trigonometric identity Sin (A+B) = SIn A cos B + Cos A sin B

So ; equation 4 can now be:

[tex]T_3 cos \theta_2 = T_1sin(\theta _1 + \theta_2)[/tex]  --- (5)

replacing equation (1) into  equation (5) ; we have:

[tex]F_g}cos \theta_2 =T_1 sin (\theta_1+\theta_2)[/tex]

Hence; the tension in the string is:

[tex]T_1= \dfrac{F_gcos \theta_2}{sin (\theta_1+\theta_2)}[/tex]

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