Isolid iron ball of mass 770kg is used on a building site. the ball is suspended by a rope from a crane. the distance from the point of suspension to the centre of the mass of the ball is 12 m. the ball is pulled back from the vertical and then realeased, it falls through a vertical height of 1.6m and strikes the wall: what is the speed of the ball just before impact?

Based on the given values above, here is the solution which I hope will be helpful to you. 
Triangles, L = 12m, x_0 = 1.6,
we need to find the angle (theta)
sin (theta) = 1.6/12 = 0.1333
theta = ArcSin(0.1333...) = 0.1337 rad
 hen, this is the height that the mass vertically raises in it's arc
y_2 = L-L*cos(theta) = 0.107 m
use y_2 in a kinematic swing... v=√2gy^2 = 1.45m/s
The speed would be 1.45m/s. Hope this answer helps.