Solving Tension in Cable Homework Statement

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SUMMARY

The discussion focuses on calculating the tension in a cable supporting an 8.6 kg sign using the equation T*L*sinΘ = mgd. The user initially calculates the tension (T) as 97 N but expresses confusion regarding the distances involved. A suggestion is made to draw a free body diagram to clarify the forces at play and to ensure the equations of static equilibrium are correctly applied. The importance of accurately defining the distances from the sign to the wall (d) and from the cable to the wall (L) is emphasized to resolve the confusion.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Familiarity with free body diagrams
  • Knowledge of trigonometric functions in physics
  • Basic concepts of tension in cables
NEXT STEPS
  • Draw and analyze free body diagrams for similar problems
  • Review static equilibrium equations in physics
  • Study the application of trigonometric functions in tension calculations
  • Explore examples of cable tension problems in physics textbooks
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This discussion is beneficial for physics students, educators, and anyone involved in mechanical engineering or structural analysis who seeks to understand tension calculations in static systems.

SilverAu
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Homework Statement


A vendor hangs an 8.6kg sign in front of his shop with a cable held away from the building by a lightweight pole. The pole is free to pivot about the end where it touches the wall,

Knight3e.ch8.p08.jpg

Homework Equations


T*L*sinΘ = mgd
where d is the distance from the sign to the wall
and L is the distance from the cable to the wall
and T the cable tension.

The Attempt at a Solution


T = mgd / sinΘ = 8.6kg * 9.8m/s² * d / Lsin60 = 97N * L/d
T = 97 N
Is this right? because I am confused on what the distance is.
 
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SilverAu said:

Homework Statement


A vendor hangs an 8.6kg sign in front of his shop with a cable held away from the building by a lightweight pole. The pole is free to pivot about the end where it touches the wall,

Knight3e.ch8.p08.jpg

Homework Equations


T*L*sinΘ = mgd
where d is the distance from the sign to the wall
and L is the distance from the cable to the wall
and T the cable tension.

The Attempt at a Solution


T = mgd / sinΘ = 8.6kg * 9.8m/s² * d / Lsin60 = 97N * L/d
T = 97 N
Is this right? because I am confused on what the distance is.

Instead of trying to decipher some formula of unknown source, why don't you draw a free body diagram of the pole supporting the sign and write equations of static equilibrium? If you do, you might find that the equation you were using is not entirely correct.
 
Is this right? because I am confused on what the distance is.
... let's see your reasoning for each step of calculation you did?
2nd what Steamking says above.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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