Question

Based on the video and your lab manual, if you already know the average angle of the measurement is 21 degree, using the average R_cm from question 2, what will be the speed Vp for the pendulum starting to leave away from the equilibrium position? (gravity constant is 9.8m/s²)

Answer 1

If we assume the potential at the point when the pendulum is at its lowest to be zero, then, When it reaches the extreme position, it rises vertically up by

h=(R_cm - R_cm cos θ )

Thus, potential energy at highest point = mg (R_cm - R_cm cos θ )

When the pendulum just leaves the equillibrium postion, its potential energy is zero, all of that is converted into kinetic energy.

Thus, using conservation of energy

we get, (1/2) m v_p² = mg (R_cm - R_cm cos θ )

Thus,

For g=9.8 m/s² and θ=21⁰ we get