A 2.5m pendulum is pulled back at an angle of 15.0 degrees and released. it's speed at the bottom of the swing is,

A) 1.29 m/s

B) 1.67 m/s

C) 6.88 m/s

D) 7.00 m/s

Conservation of mechanical energy:

Down is all kinetic, when released is all potential:

1/2*m*v^2 = mgh, the initial height h = L (1-cos (alpha)) (nice to think why)

so, v^2 = 2gL (1-cos (alpha))

v = sqrt (2gL (1-cos (alpha)) = sqrt (2*10*2.5 * (1-cos (15))

Beware of having the calculator in degrees

v = sqrt (50 * 0.0341) = 1.305 m/s

It is A) and they may have used 9.81 m/s^2 instead of 10 m/s^2