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gmmstr827
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Homework Statement
A 100g pendulum bob hangs from a 1 meter string. What is the tension in the string when the pendulum is not moving (i.e. at the 'bottom')? What is the tension when it is at 30° to the vertical?
Homework Equations
100g=.1kg
g=-9.8m/s^2
F_t=-mgcos(Θ)
The Attempt at a Solution
Tension when not moving:
F_t=-mgcos(Θ)=-(.1kg)(-9.8m/s^2)cos(0)=.98N
Tension at 30° to the vertical:
F_t=-mgcos(Θ)=-(.1kg)(-9.8m/s^2)cos(30°)≈.15N
Is that correct?
My main dilemma is that my professor told us when a pendulum exceeds a 15° swing angle, that it can no longer be considered a simple pendulum and goes by more complicated physics, however, this pendulum swings to twice that angle.
Also, when I put this on a different site, someone answered and said "The tension at any angle cannot be known unless you also know its velocity at that point."
Thoughts?