A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom of its swing

m g h = 1/2 m v^2     potential energy will be converted to kinetic energy

h = h0 (1 - cos theta)    where theta is the displacement

theta = 30 / 50 = .6        theta = 36.9 deg        

v^2 = 2 g h    from above

h = 50 (1 - cos 36.9) = 50 * .2 = 10 cm

v = (2 * 980 * 10)^12 = 140 cm/sec

a and c

c is 100% but i am confused in a

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