What Is the Vertical Acceleration at the Lowest Point of a Swinging Pendulum?

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At the lowest point of a swinging pendulum, the vertical acceleration is not simply -9.8 m/s² due to the influence of tension in the supporting string or rod. The force of gravity acts downward, but the tension counteracts it, affecting the net force. To accurately determine the vertical acceleration, additional information about the tension in the rod is required. The relevant equation to consider is ΣF=ma=mg-T Cos θ, which incorporates both gravitational force and tension. Therefore, without knowing the tension, the vertical acceleration cannot be conclusively calculated.
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original pendulum of mass 11 kg with a period of 1.6 sec, displaced an angle of 12 degrees from the vertical. What would its acceleration be in the vertical (y) direction as it reachs the lowest point on its swing?

wouldn't it just be -9.8? (since its just the force of gravity acting on it)
 
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It is a pendulum, which means it is attached by a rod or string. In either event, what does that do to the force of gravity at the low point?
 


umm...not sure...
 


Well if you look at the free body diagram the tension in the rod cancels out the force of gravity.
 


ok so its just zero
 


yep.
 


you need more information to solve the problem. you need to know the tension in the rod or string that's supporting the pendulum. Then you will be able to solve the eqn
ΣF=ma=mg-T Cos θ
 
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