A frictionless pendulum has a length of 1.2 m and a mass of 0.8 kg. If the pendulum is raised to an angle of 50 degrees before it is released, then what is the pendulum’s gravitational potential energy at the point of release? A. 3.4 J
B. 2.2 J
C. 6.0 J
D. 0.34 J

At the bottom    h = 0   for pendulum

at the top           h = L - L cos 50     height to which pendulum raised

   h = L (1 - cos 50) = 1.2 * .357 = .429 m

potential energy = m g h

PE = .8 kg * 9.8 m/s^2 * .429 m = 3.4 J

answer: a) y=-8x+5

a) m= -8

b) m= -2

c) m= 7

d) m= 6