A tugboat tows a ship at a constant velocity. The tow harness consists of a single tow cable attached to the tugboat at point A that splits at point B and attaches to the ship at points C and D. The two rope segments BC and BD angle away from the center of the ship at angles of ϕ = 26.0 ∘ and θ = 21.0 ∘, respectively. The tugboat pulls with a force of 1200 lb . What are the tensions TBC and TBD in the rope segments BC and BD?

Respuesta :

Answer:

The tensions in [tex]T_{BC}[/tex] is approximately 4,934.2 lb and the tension in [tex]T_{BD}[/tex] is approximately  6,035.7 lb

Explanation:

The given information are;

The angle formed by the two rope segments are;

The angle, Φ, formed by rope segment BC with the line AB extended to the center (midpoint) of the ship = 26.0°

The angle, θ, formed by rope segment BD with the line AB extended to the center (midpoint) of the ship = 21.0°

Therefore, we have;

The tension in rope segment BC = [tex]T_{BC}[/tex]

The tension in rope segment BD = [tex]T_{BD}[/tex]

The tension in rope segment AB = [tex]T_{AB}[/tex] = Pulling force of tugboat = 1200 lb

By resolution of forces acting along the line A_F gives;

[tex]T_{BC}[/tex] × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = [tex]T_{AB}[/tex] = 1200 lb

[tex]T_{BC}[/tex] × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = 1200 lb............(1)

Similarly, we have for equilibrium, the sum of the forces acting perpendicular to tow cable = 0, therefore, we have;

[tex]T_{BC}[/tex] × sin(26.0°) + [tex]T_{BD}[/tex] × sin(21.0°) = 0...........................(2)

Which gives;

[tex]T_{BC}[/tex] × sin(26.0°) = - [tex]T_{BD}[/tex] × sin(21.0°)

[tex]T_{BC}[/tex] = - [tex]T_{BD}[/tex] × sin(21.0°)/(sin(26.0°))  ≈ - [tex]T_{BD}[/tex] × 0.8175

Substituting the value of, [tex]T_{BC}[/tex], in equation (1), gives;

- [tex]T_{BD}[/tex] × 0.8175 × cos(26.0°) + [tex]T_{BD}[/tex] × cos(21.0°) = 1200 lb

- [tex]T_{BD}[/tex] × 0.7348  + [tex]T_{BD}[/tex] ×0.9336 = 1200 lb

[tex]T_{BD}[/tex] ×0.1988 = 1200 lb

[tex]T_{BD}[/tex] ≈ 1200 lb/0.1988 = 6,035.6938 lb

[tex]T_{BD}[/tex] ≈ 6,035.6938 lb

[tex]T_{BC}[/tex] ≈ - [tex]T_{BD}[/tex] × 0.8175 = 6,035.6938 × 0.8175 = -4934.1733 lb

[tex]T_{BC}[/tex] ≈ -4934.1733 lb

From which we have;

The tensions in [tex]T_{BC}[/tex] ≈ -4934.2 lb and  [tex]T_{BD}[/tex] ≈ 6,035.7 lb.