posted by waqas .
A pendulum of length L = 20.8cm and mass m = 168 g is released from rest
when the cord makes an angle of 65.2 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?
a) what is L(1-cos65.2) ? think why I asked that, draw the figure.
b) What is mgh
c) Isn't string tension always at 90 degrees to the movement of the mass? Work is force*distance*cosAngleBetweenThem.