A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Physics;accounting for tension of a pulley on frictionless surface.

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Tension of the pulley is calculated using........

  3. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    newtons laws of motion

  4. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    applying newtons law to the whole system force = mass * acceleration 6*g = 11 * a a = 6*9.8 /11 = 5.35 m s-2

  5. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    now i know how to find the tension in the string considering the horizontal string applying newtons second law;- Tension = 10 * 5.35 = 53. 5 N

  6. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    but you require tension in the pulley right?

  7. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i think its mg= 6*9.8=tension on the string since the is no effect of 5 kg wt. as surface is frictionless

  8. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    sorry i dont know where i got 10 from!!!!

  9. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    if you consider the horizontal string its 5 * 5.35 not 10 * 5.35

  10. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    hhmm.. i'm not sure I would have thought you would have to take the 5 kg into account. Its been a long time since i did these...

  11. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella how can you add 6+5= 11 to get 11*a this is not the case actually...

  12. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    but i'mm considering the whole system 5 kg and 6 kg are part of the whole system

  13. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    6 g is the downward force (dues to 6 kg mass) but 5kg is part of the mass

  14. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the tension will be the same throughout the whole string so i guess thats also the force on the pulley

  15. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    5kg would have created friction on the surface due to wt. which would hav then created a resistance to allow the whole system to move down....this would hav decreased the tension on the string but here the surface is frictionless...

  16. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    hmm maybe but i dont think you can ignore the 5 kg...

  17. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    maybe i'm wrong

  18. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I'd have to look it up

  19. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1439391345545:dw|

  20. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    https://www.youtube.com/watch?v=e2-yHHSzjTs - this is about a similar problem

  21. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no effect of the 2 forces on each other due to surface is frictionless...

  22. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    if you check out the above link you'll see i'm right The 5kg has to be taken into account

  23. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    there is a tension between the 2 masses - the tension in the string

  24. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    may be you are right....i got confused...i hav to think again on it....

  25. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    its a tricky subject I wasn't sure but the link gives a good explanation.

  26. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella yes your were right....i hav checked my book...my doubt is cleared....i am sorry that i wasted your time....but thanks....

  27. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    No you didn't waste my time - I had to make sure I was right also!!

  28. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yw

  29. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Hey guys thanks for all your insights

  30. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    This kind is one of the most counterintuitive

  31. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Therefore so far to our best of knowledge tension 11kg*5.35m/^2

  32. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I am crying right now

  33. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes - its s a bit hard to visualive - If the mass of the object on the table was say 15 kg there would still be motion because the table is frictionlass

  34. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    according to inertia that is.

  35. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So it naturally falls upon us to calculate the acceleration and corresponding weight of the whole system

  36. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Because tension is responsible for holding two masses which sum up to kg. Tension holds them from falling apart after all. Given that one side of the tension is pulling the system both masses are involved in the motion of the whole system.

  37. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes

  38. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    You established that "connection" with me here. Universal law of affection of physics applies to all of usXD

  39. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    we've found that the acceleration is 5.35 m s-2 but now we have to find the tension

  40. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Isn't the tension 11kg*5.35m/s^2?

  41. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    most intuitively

  42. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    But tension on the pulley... I don't know

  43. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that's the hardest part of this question is "tension on the pulley" instead of tension of the line.

  44. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well the units of the tension will be N Newtons

  45. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    * will be in Newtons

  46. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    see what i hav checked in my book, (m1+m2)a = m2*g T= m2*g - m2*a

  47. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yea that looks good

  48. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    T= m1*a

  49. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Your equation assumes that overall force required to move the entire system is equivalent to the force exerted by a mass due to gravity.... Ok. This holds true on frictionless surface I suppose.

  50. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    *overall force required to accelerate

  51. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    so its 5 * 5.35 N?

  52. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    11*5.35m/s^2 assumes normal force is ignored?

  53. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes normal force acts perpendicular to motion so can be ignored

  54. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    No I think you should consider the "tension" which is induced by the 6kg mass as well. To assume there is only 5kg being responsible for the tension is absurd because it's not the only factor pulling the line.

  55. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella got you .

  56. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Michele_Laino

  57. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    People say he's a physicist so

  58. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    can we apply newtons second law to the 5 kg mass in isolation? in which case we can say T = 5 * 5.35 = 26.75 N ?

  59. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    - why can't we do that?

  60. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    - that gives the tension in the horizontal string

  61. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    The prospect of assuming the tension to be "stretched" is somehow absurd?

  62. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    *5.35m/^2

  63. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I think that reason why 6kg object is considered is because it's the source of force.

  64. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I'll have to look at another video lol! I'm not saying you guys are wrong but i'm not convinced.

  65. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella you are right T= 5 * 5.35 N

  66. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I;ll give you a medal for saying that lol!

  67. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So it's not the initial 11kg*5.35m/s^2

  68. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    but rather the second one.

  69. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I'd like to giv medal to Robert also but it wont let me...

  70. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that is final @welshfella is right...

  71. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks so much physics aficionados I think I understand it now.

  72. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Robert136 do you got it?

  73. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yea the more i think about it.... the horizontal tension pulls the 5 kg mass so T must = mass * a = 5 * 5.35

  74. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the more I think about it the better it settles in my brainXD

  75. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    but thats the tension in string what about the pulley? T acts directly on the pulley so that makes T on pulley = 26.75 N also?

  76. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Right the tension is essentially moving the 5kg mass on frictionless surface so the tension must only account for the 5kg and greater acceleration implies proportionally valid force being applied. Ha! I think that's our ultimatum

  77. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella your above statement is true...

  78. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well guys we've learnt something with this session Good

  79. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    nice!

  80. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    The pulley is more like the center of this system at 90 degree angle. What if it was 180 degrere angle we all know to be the same?

  81. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Since frictionless the direction must not matter ??

  82. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    right

  83. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Mechanical advantage says it takes one half of force if pulley is used in two fold like manner. But I guess this doesn't concern this partiuclar problem...

  84. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Its coming back to me now - after all these years - I wont say how many (lol!!)

  85. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Physics is the protein bar for the intelligence

  86. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Where intuition fails all the time. problem of this kind makes me reflect on my life from more logical poin of view.

  87. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thanks all bye!

  88. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks everyone!

  89. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the pulley must also be frictionless for the tension throughout the string to be uniform

  90. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yw

  91. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    uniform acceleration that is

  92. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Where veocity time graph would have a positive slope.

  93. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Do you remember that stuff??

  94. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    some of it yes acceleration = rate of change of velocity = slope

  95. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    and distance traveled = area under the graph

  96. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    uniform velocity is indicated by a straight line with a positive slope

  97. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    * sorry that's uniform acceleration

  98. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yeah whereas friction would prevent that

  99. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    One quick recap on this thread; when we did the calculation on acceleration of the whole system we used the sum of both masses.... is that accurate?

  100. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    As in 6.0kg*9.8m/s^2=11a as opposed to 5a just like what we did in the last counterpart.

  101. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    The object being acted upon is the 5.0kg mass accelerating... hmm my brain is such a pelletty equipment.

  102. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes we dealt with the whole system as we have no friction it was just like everything was horizontal with the force of gravity 6g acting on whole system and a weightless rigid body connecting the 2 masses

  103. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    |dw:1439398166592:dw|

  104. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the double arrows indicate acceleration

  105. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the force acting is 6g mass * acceleration due to gravity

  106. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok. I get it. But how's that related to having only the 6kg object as being responsible for the entire system? I feel like 5.0kg is being "pulled" rather than moving "together" with the 6.0kg object. HmmmI guess I am really dumb

  107. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the force has to accelerate the total mass which is 11 kg

  108. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes the 5 kg is being pulled by the tension in the string which is caused by the downward force of the 6 kg weight. I f there was no weight on the table the acceleration would be much greater . The 5 kg slows the whole system down. bit it is part of the system .

  109. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    If its weight was say 50 kg the system would still be in motion but acceleration would be a lot less.

  110. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    It is intuitive to a degree because the heavier the mass the acceleration would be a lot slower - because the force is constant at 6 g N but the mass is greater

  111. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    you can also find the tension in the string by considering the mass of 6 kg without referring to the 5 kg |dw:1439398934381:dw|

  112. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Tension can be calculated with 6kg using the acceleratoin?

  113. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the tension is working against the force 6g so the net force = 6g - T applying the second law 6*9.81 - T = 6 * 5.35 T = 26.76 N

  114. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes its valid to consider both masses separately

  115. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    in fact we could have found T and a by using 2 system of equations 6.g - T = 6 a - for the g kg mass T = 5a - for the 5 kg mass

  116. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    so we could have found T and a together

  117. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    adding we get 6g = 11a a = 6g/11 = 5.35 then T = 5 8 5.35 = 26.75

  118. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    * 5 * 5.35 = 26.75

  119. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    its all coming back now

  120. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    We all strive to find that momentXD Nostalgia old schoolXD

  121. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yea lol!!

  122. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Yea we had a very good math teacher. Our school was a very good one one - in Swansea UK. II guess its most famous pupil was Dylan Thomas the poet

  123. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Awesome! I miss going to american schools:)

  124. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Not that he was any good at Math. He was exceptional at English and cared nothing about anything else.

  125. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yea At the time you didn't realize how good those days were.

  126. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Have you ever heard recordings of Dylan Thomas reciting poetry? Some people don't like the way he reads them others find it awesome.

  127. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Dylan Thomas don't gentle into that good night. Old age should rage at close of day. Rage rage rage into that good night.

  128. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yea that's his most famous poem.

  129. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    It's so true though.

  130. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Well id better feed the cat. She's in charge!! Yes. His father was the English teacher in the school and its to him the poem was written.

  131. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yeah every time I read his poem it makes me regret and realize so much I missed in life

  132. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yep

  133. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I guess I am supposed to be raging and raving but every day seems o be the reality of inevitable time passing.

  134. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I wish I could have more emotions at work and assign a meaning to every day each day until I die. I guess travelling seems to be the best option for all of us.

  135. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I think we waste a lot of time thinking about what we are going to do but never do it. Yea If you can afford it travel is great.

  136. welshfella
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    nice talking to you must go

  137. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Likewise! Thank so much for your help:) See you around.

  138. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.