- #26

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I am just evaluating question 3 and then will reply to you with my thoughts...

Thank you very much for all of your help I really appreciate it

- Thread starter lpettigrew
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- #26

- 88

- 4

I am just evaluating question 3 and then will reply to you with my thoughts...

Thank you very much for all of your help I really appreciate it

- #27

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This is a reasonable model as the extension of the rope is likely to be small so the assumption that the string is inextensible is fitting. Moreover, the statement that there is no resistance in the moving parts of the cart is reasonable if the cart is in optimal working order and is adequately maintained. Although, the model could be refined to take into account that the string may extend. Additionally, it may be preferable to account for the friction and other forces acting due to the moving parts of the cart at a later stage. Moreover, the string may be considered light (meaning that since its mass is very small compared to the other masses in question we can take it to be zero) since weight if the horses and cart far exceeds that of the string. It would also be worthy to take into account the mass of the horses and cart.

- #28

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Using this model, what would the tension be in the ropes? Is that realistic?

This is a reasonable model as the extension of the rope is likely to be small so the assumption that the string is inextensible is fitting. Moreover, the statement that there is no resistance in the moving parts of the cart is reasonable if the cart is in optimal working order and is adequately maintained. Although, the model could be refined to take into account that the string may extend. Additionally, it may be preferable to account for the friction and other forces acting due to the moving parts of the cart at a later stage. Moreover, the string may be considered light (meaning that since its mass is very small compared to the other masses in question we can take it to be zero) since weight if the horses and cart far exceeds that of the string. It would also be worthy to take into account the mass of the horses and cart.

- #29

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Would the tension be T=mg+ma? Or would it be that the tension is negligible?

- #30

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The question says constant speed. And nothing about going up hill.Would the tension be T=mg+ma? Or would it be that the tension is negligible?

- #31

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- #32

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Where do these forces come from?

- #33

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Sorry, I made a mistake, I mistook the acceleration as constant not the speed. I have puzzled myself.That's an intetesting take. If I see constant speed in a question I assume acceleration is zero.

Where do these forces cone from?

- #34

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If the speed is constant then the acceleration would be zero. In accordance with F=ma, if a is zero, then F will zero and since the tension is proportional to the acceleration, would it is also be zero?

Where do these forces come from?

- #35

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Yes.If the speed is constant then the acceleration would be zero. In accordance with F=ma, if a is zero, then F will zero and since the tension is proportional to the acceleration, would it is also be zero?

- #36

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- #37

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Yes. Although "realistic" might be subtly different from good. Personally, I think c) is a poor question, since it's not clear what is the point of this model. What is the relevance of a small amount of tension in the ropes? As opposed to zero tension. What does it matter?

A better question would be a car at constant speed with no resisting forces. Then, the model would be bad because it would predict zero fuel consumption. That model would be practically useless.

- #38

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Yes. Although "realistic" might be subtly different from good. Personally, I think c) is a poor question, since it's not clear what is the point of this model. What is the relevance of a small amount of tension in the ropes? As opposed to zero tension. What does it matter?

A better question would be a car at constant speed with no resisting forces. Then, the model would be bad because it would predict zero fuel consumption. That model would be practically useless.

If the tension in the rope is proportional to the acceleration (which is zero), would this be like assuming the rope is tense and completely stationary since the force pulling the the rope by the horses must be balanced by an equal force pulling from the cart? The force of tension would act on an object opposing its movement and reducing its speed. Therefore, the significance of there being some tension, even a small amount, as opposed to zero tension is that it reduces the speed with which the horse and cart travel?

So I could state that this model is poor since finding the tension in the ropes has little effect on the motion of the cart. The model could be refined to take into account that the string may extend. Additionally, it may be preferable to account for the friction and other forces acting due to the moving parts of the cart at a later stage. Moreover, the string may be considered light (meaning that since its mass is very small compared to the other masses in question we can take it to be zero) since weight if the horses and cart far exceeds that of the string. It would also be worthy to take into account the mass of the horses and cart.

Although the extension of the rope is likely to be small so the assumption that the string is inextensible is fitting. Moreover, the statement that there is no resistance in the moving parts of the cart is reasonable if the cart is in optimal working order and is adequately maintained. It may be better to neglect the tension in the ropes since when the cart moves with constant speed the acceleration is equal to zero. According to F=ma, the force of the tension will be proportion to the acceleration, here being zero, so it is futile finding the tension if it has no effect.

- #39

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Maybe you could say that more simply!

- #40

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Finding the tension in the ropes has little effect on the motion of the cart, since it is equal to zero, therefore, it may be better to neglect the tension in the ropes.

The model could be refined to take into account that the string may extend. Additionally, it may be preferable to account for the friction and other forces acting due to the moving parts of the cart at a later stage.

- #41

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- #42

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- #43

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Could you give an example? I am working on this but tend to include too much information.

- #44

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"This model is poor since it is states that the speed with which the cart travels is constant, menaing the acceleration is zero. Since the acceleration is proportional to the tension, this would mean that the tension in the rope is also equal to zero. therefore, it would be pointless to mathematically prove this.

Finding the tension in the ropes has little effect on the motion of the cart, since it is equal to zero, therefore, it may be better to neglect the tension in the ropes.

The model could be refined to take into account that the string may extend. Additionally, it may be preferable to account for the friction and other forces acting due to the moving parts of the cart at a later stage."

- #45

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Go with that.

- #46

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Should I not improve it somehow?

- #47

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That's up to you.

- #48

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I am not sure how but I want to, I do not feel that it suitably and fully answers the question

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