• Consider the track shown in figure. The section "AB" is one quadrant of a circle (1/4 circle) of radius 2 m and is frictionless. B to C is a horizontal span L=3 m long with a coefficient of kinetic friction μ k=0,25. The section CD under the spring is frictionless. A block of mass 1 kg is released from rest at A. After sliding on the track, it compresses the spring by x=0,2 m. Determine: a) the velocity of the block at point B; b) the velocity of the block at point C; cd) the stifthess constant k for the spring.