Amplitude of 3-kg Pendulum 2m Arc 21.4°

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The discussion revolves around calculating the amplitude of a 3-kg pendulum with a 2-meter length that swings through a half arc of 21.4 degrees. There is confusion regarding the terms "half arc" and "amplitude," with participants seeking clarification. One participant suggests using the formula for arc length, stating that the amplitude can be derived from the radius and angle. The calculated amplitude is approximately 74.66 cm. The conversation emphasizes the need for understanding kinetic and potential energy changes in solving the problem.
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A pendulum has a mass of 3-kg, a length of 2 meters and swings through a (half)arc of 21.4 degrees. What is its Amplitude to the nearest centimeter ?

i don't undretand the queston; half arc? amplitude?

and how would you use kinetic/potential energy change to solve this porblem? i really don't understand this qusetion i'd really likea couple of hints and tips for this problem thanks a lot
 
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74.66 cm
arc=radius*angle
 
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