(10 Points)6.-You have built a ramp with sections that are frictionless and with other sections that are rough and therefore there is friction. You have a 1.86-kg block as shown in the drawing below. The block is held in place against the spring by a 81-N horizontal external force(see the figure). The external force is removed, and the block is projected with a velocityvl = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity v2 = 1.9 m/s at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction over this section is 0.28. The velocity of the block is v3 =1.4 m/s at C. The block moves on to D, where it stops. What is the height h of the ramp?

Fig: 1

Fig: 2