A ball of mass 
is held between two fixed points A and B by two stretched helical springs, as shown in the figure below.
The ball oscillates along the line AB with simple harmonic motion of frequency 
and amplitude 
.
Show that the total energy of the oscillations is 
.
At two points in the oscillation of the ball, its kinetic energy is equal to the potential energy stored in the springs. Calculate the magnitude of the displacement at which this occurs.
.
