Posted by secret on Wednesday, May 12, 2010 at 8:17am.
a pendulum has a bob of 0.20kg and is suspended by a string of negligible mass near the earth's surface. the pendulum is displaced from its equilibrium position by the angle of 8.0 degrees. it passes the equilibrium position 0.50 s after being released. calculate the length of the pendulum,max. kinetic energy and max. velocity of the bob!

Physics  drwls, Wednesday, May 12, 2010 at 9:36am
Get the length L from the period P.
The period is 2 seconds because it takes 1/2 second to accomplish 1/4 of it. (maximum deflection to zero deflection)
P = 2 pi sqrt(L/g)= 2 seconds
L/g = (1/pi)^2
L = 0.994 m
The maximum height that it gets raised is
h = L (1  cos 8) = 0.00967 m
The maximum K.E. is M g h (which is the maximum potential energy)
Use that to compute Vmax