I did it but a little more understanding needed

  • Thread starter neelakash
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In summary, the conversation discusses two problems involving a block on an inclined plane with an external force and friction. The first problem calculates the force needed to get the block started while the second problem finds the maximum value of M/m for equilibrium. The question arises about what happens when tanθ<μ. The conversation also touches on the concept of friction adjusting itself to prevent motion and the implications of F<0 or M/m<0. The conversation ends with a request for clarification and understanding on the topic.
  • #1
neelakash
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1

Homework Statement



It is a sort of looking back...that I am doing these old problems.However,I have attached the figures in the pdf file...where the diagram of the two problems are given.I included two problems as my question is a single one that is common to these two problems.

In the 1st one,mass of the block=m.The normal force N acts upward.External force F inclined at an angle θ to the vertical.Friction co-eff μ.Force F needed to get the block just started is (This is the first part of the problem and I have calculated this)
F=μmg/[sinθ-μ cosθ]

In the 2nd one,I found out the maximum value of M/m so that the system is at rest.M is the mass on the inclined plane.Friction co-eff is μ.
the maximum value is M/m= μ/[sinθ-μ cosθ]


My question here is what will be the situation when tanθ<μ

Homework Equations


The Attempt at a Solution



The condition means (f/N)<μ or,f<μN or,f<f(max)

In the 1st problem it means that friction has not yet attained the maximum value and we must have the block in equilibrium...That is friction automatically adjusts itself to be equal and opposite to F sinθ all the time.I mean we increase the value of F and friction being equal and opposite,no motion results.And with tanθ<μ,we cannot increase F to that value as obtained...

Now I am not sure that my explanation conforms that given in the book.It is a worked out example,in fact.
The condition also means that F<0 as I calculated.They say that "for angles less than θ,one cannot push the block ahead,however large the force may be".

In the 2nd problem,I will say that friction< maximum possible value of friction and that means that it will adjust itself such that no motion would occur.That it friction will be equal and opposite to the resultant of (mg sinθ-T).

Here the book says "since at the condition M/m ratio<0,hence,no motion would occur"...


My point in these two problems is that F<0 or, M/m<0 might imply that tanθ<μ leads to such bizarre result...It may be that the two explanations are equivalent...please help me in better understanding...
 

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  • #2
neelakash said:

Homework Statement



It is a sort of looking back...that I am doing these old problems.However,I have attached the figures in the pdf file...where the diagram of the two problems are given.I included two problems as my question is a single one that is common to these two problems.

In the 1st one,mass of the block=m.The normal force N acts upward.External force F inclined at an angle θ to the vertical.Friction co-eff μ.Force F needed to get the block just started is (This is the first part of the problem and I have calculated this)
F=μmg/[sinθ-μ cosθ]

In the 2nd one,I found out the maximum value of M/m so that the system is at rest.M is the mass on the inclined plane.Friction co-eff is μ.
the maximum value is M/m= μ/[sinθ-μ cosθ]


My question here is what will be the situation when tanθ<μ

Homework Equations


The Attempt at a Solution



The condition means (f/N)<μ or,f<μN or,f<f(max)

In the 1st problem it means that friction has not yet attained the maximum value and we must have the block in equilibrium...That is friction automatically adjusts itself to be equal and opposite to F sinθ all the time.I mean we increase the value of F and friction being equal and opposite,no motion results.And with tanθ<μ,we cannot increase F to that value as obtained...

Now I am not sure that my explanation conforms that given in the book.It is a worked out example,in fact.
The condition also means that F<0 as I calculated.They say that "for angles less than θ,one cannot push the block ahead,however large the force may be".

In the 2nd problem,I will say that friction< maximum possible value of friction and that means that it will adjust itself such that no motion would occur.That it friction will be equal and opposite to the resultant of (mg sinθ-T).

Here the book says "since at the condition M/m ratio<0,hence,no motion would occur"...


My point in these two problems is that F<0 or, M/m<0 might imply that tanθ<μ leads to such bizarre result...It may be that the two explanations are equivalent...please help me in better understanding...

I am not able to see the figure
 
  • #3
I am sorry,but I can see the file named Doc1.pdf.

However,I attached it once more.
Hope now you will be able to see it.

<original file approved--Doc Al>
 
Last edited by a moderator:

1. What does "I did it but a little more understanding needed" mean?

"I did it but a little more understanding needed" is a phrase commonly used to express that the speaker has successfully completed a task, but still requires further knowledge or clarification on the subject.

2. How do you know when you need a little more understanding?

You may need a little more understanding when you have completed a task but still feel unsure or confused about certain aspects of it. This could be due to lack of knowledge, experience, or resources.

3. Can you give an example of a situation where "I did it but a little more understanding needed" would apply?

Sure, let's say you are trying to bake a cake for the first time and you follow a recipe but it doesn't turn out quite as expected. You may say "I did it but a little more understanding needed" to indicate that you were able to bake a cake, but you still need to learn more about baking techniques for a better result.

4. How can "I did it but a little more understanding needed" be beneficial?

"I did it but a little more understanding needed" can be beneficial in acknowledging your progress and success while also recognizing areas where you can improve and continue learning. It can also open up opportunities for collaboration and seeking guidance from others.

5. Is it important to seek more understanding even after completing a task?

Yes, seeking more understanding even after completing a task can lead to continuous growth and improvement. It also shows a willingness to learn and improve, which can be beneficial in personal and professional development.

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