Here is an acceleration-time history that will cause the mass to fall to each end of the slot along the X axis.
t (s) ax(m/s^2)
0.0 -9.81
1.0 -9.81
1.00001 9.81
2.0 9.81
2.00001 -9.81
3.0 -9.81
3.00001 9.81
4.0 9.81
... ...
this shows the first four impacts.