A spring with a spring-constant 3.4 N/cm is compressed 27 cm and released. The 9 kg mass skids down the frictional incline of height 13 cm and inclined at a 17◦ angle. The acceleration of gravity is 9.8 m/s2 . The path is frictionless except for a dis- tance of 0.5 m along the incline which has a coefficient of friction of 0.2. What is the final velocity vf of the mass?