Calculate the speed of the particle

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To calculate the speed of a particle in a simple pendulum, one can apply the conservation of energy principle, equating gravitational potential energy and kinetic energy. For the lowest point in the trajectory, the speed can be derived from the height difference, using the formula for kinetic energy. When the pendulum is at an angle of 15.0°, the height can be calculated from the angle and string length, allowing for speed determination at that position as well. The discussion also raises questions about the assumptions regarding gravity and the mass of the string, emphasizing the need for clarity in the problem's context. Ultimately, applying the correct energy formulas will yield the desired speed calculations.
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A simple pendulum, consists of an object suspended by a string. The object is assumed to be a particle. The string, with its top end fixed, has negligible mass and does not stretch. In the absence of air friction, the system oscillates by swinging back and forth in a vertical plane. If the string is 2.70 m long and makes an initial angle of 30.5° with the vertical, calculate the speed of the particle at the following positions.

(a) at the lowest point in its trajectory

(b) when the angle is 15.0°


I thought I could use ac = V^2/r.. but I got the wrong answers
anyone have any hints for me on what I use for formulas?
 
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Try conservation of energy (gravitational potential energy and kinetic energy). Take the bottom position as your reference point.
 
In free space, umm it doesn't.

You have a hypothetical string of no mass in with a hypothetical end point. Are we to assume it is in a hypothetical Earth gravity or some other space?
 

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