Why Does the Pendulum Angle Calculation Show 60° Instead of 30°?

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cupid.callin
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Homework Statement


Problem text with answer options A to D beside a diagram of a ring on a fixed horizontal rail, with a string of length l hanging from it to a particle of mass m.



The Attempt at a Solution



Here my figure showing forces:

Free-body diagram of a pendulum bob hanging from a support accelerating to the right with acceleration a0, showing tension T at angle θ0 from vertical, components Tcosθ0 upward and Tsinθ downward-right, and weight mg downward.


SO here,

Tcosθ = mg
Tsinθ = mao

so tanθ =ao/g = 1/√3

so θ = 30o, right?

but it answer says its 60o
 
Attachments
  • Physics problem text with a diagram of a ring on a fixed smooth horizontal rail, a string of length l hanging down to a particle of mass m; options listed include θ0 = 30° and θ0 = 60°, tension mg/2, and tension 2mg/√3.
    Untitled 2.jpg
    19.9 KB · Views: 466
  • Free-body diagram of a pendulum bob hanging from a pivot on a ceiling that accelerates to the right with a0. Forces on the bob: tension T along the string, T cos θ vertically up, T sin θ horizontal, and mg downward. Angle θ0 is marked between the string and the vertical.
    Untitled.png
    22.6 KB · Views: 519

Discussion

that can't be
book hasn't been wrong ever till now (and i have done like 80% of it)
 

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