# A boat being pulled by two other boats with cables

• Lay1
In summary, the student was asked to solve a problem, but the diagram they provided was inaccurate and confusing.
Lay1
Homework Statement
A ship is pulled at a constant speed by two small boats, A and B, as shown in Figure 4.27. The engine of the
ship does not produce any force. The tension in each cable between A and B and the ship is 4000 N.
a. Draw a free-body diagram showing the three horizontal forces acting on the ship.
b. Draw a vector diagram to scale showing these three forces and use your diagram to find the value
of the drag force on the ship
Relevant Equations
Fx = Fcos n
Fy = Fsin n
FAx = F cos 40
FAy = F sin 40
2FAx = Drag
Drag = 6128N

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Your solution looks like one of those things you get during an eye test when the letters get smaller and smaller until you can't read them!

Tea_Aficionado, Steve4Physics, DaveC426913 and 2 others
My spreadsheet says ##2*4000\cos(40) = 6128##.

MatinSAR
Lay1 said:
Drag = 6128N
I think it should be 2(4000)cos40=6128.35N (40 degree)
It is better to share a picture from the answer which suggests it's 6200N.

The answer to me looks like one of those cases where the answer has rounded the intermediate result from 3064 N to 3100 N and then multiplied the rounded result by two, resulting in an erroneous rounding to 6200 N instead of 6100 N for the final result.
(Also note that 6128 N is too many significant digits given the precision of the input.)

hutchphd
PeroK said:
Your solution looks like one of those things you get during an eye test when the letters get smaller and smaller until you can't read them!
This is what happens when one only cancels one out of two subscript tags ...

Lay1 said:
Homework Statement
a. Draw a free-body diagram showing the three horizontal forces acting on the ship.
b. Draw a vector diagram to scale showing these three forces and use your diagram to find the value of the drag force on the ship

b) From the question's wording, it looks like you are expected to solve the problem using a scale diagram (not by using trig'). You need a pencil, paper, ruler and protractor. Don't forget to label the diagram appropriately, write the scale you are using, and give your working.

hutchphd, MatinSAR and PeroK
The diagram shown by the OP is quite inaccurate. The angles look like <30 degrees. This will lead to confusion

hutchphd said:
The diagram shown by the OP is quite inaccurate. The angles look like <30 degrees. This will lead to confusion
Since the student is asked to draw an accurate diagram, the book diagram will be deliberately a little inaccurate.

hutchphd
PeroK said:
Your solution looks like one of those things you get during an eye test when the letters get smaller and smaller until you can't read them!
I don't know why it turns out like that also.

Orodruin said:
This is what happens when one only cancels one out of two subscript tags ...
PeroK said:
My spreadsheet says ##2*4000\cos(40) = 6128##.
Thanks. Next time I will be careful about the words.

## 1. How does a boat being pulled by two other boats with cables work?

When a boat is being pulled by two other boats with cables, it utilizes the principles of tension and force. The two boats pulling the boat with cables create a tension force on the cables, which then transfers to the boat being pulled. This force helps to move the boat in the desired direction.

## 2. What are the benefits of using two boats to pull a boat with cables?

Using two boats to pull a boat with cables allows for a more even distribution of force, making it easier to control the direction and speed of the boat being pulled. It also allows for more control in case of unexpected changes in the water or weather conditions.

## 3. How are the cables attached to the boats?

The cables are typically attached to the boats using strong and secure anchor points, such as cleats or winches. These anchor points are designed to withstand the tension force created by the pulling boats and keep the cables securely attached.

## 4. What precautions should be taken when using a boat pulled by two other boats with cables?

It is important to ensure that the cables are properly secured and that all boats involved are in good working condition. It is also important to communicate effectively between all boats to ensure safe and coordinated movements. Additionally, it is crucial to be aware of any potential hazards in the water and to have a plan in place in case of emergencies.

## 5. Can any type of boat be pulled by two other boats with cables?

The type of boat that can be pulled by two other boats with cables depends on the size and strength of the boats involved, as well as the conditions of the water. It is important to consider the weight and size of the boat being pulled and ensure that the pulling boats are capable of handling the load. It is also important to take into account the weather and water conditions to ensure safe and successful towing.

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