A pendulum of length L=26.0 cm and mass m= 168 g is released from rest when the cord makes an angle of 65.2 degrees with the vertical. (a) How far (m) does the mass fall before reaching its lowest point. (b) How much work (J) is done by gravity as it falls to its lowest point? (C) How much work (J) is done by the string tension as it falls to its lowest point?

Question

A pendulum of length L=26.0 cm and mass m= 168 g is released from rest when the cord makes an angle of 65.2 degrees with the vertical. (a) How far (m) does the mass fall before reaching its lowest point.  (b) How much work (J) is done by gravity as it falls to its lowest point? (C) How much work  (J) is done by the string tension as it falls to its lowest point?

drwls · Accepted Answer

a) 26.0 cm(1 - cos65.2) = 15.1 cm b) MgH = 0.168*9.8 *0.151 = ___ J c) The string does zero work, because tension is always perpendicular to motion