A solid sphere of mass 4.0 kg and radius 0.12 m starts from rest at the top of a ramp inclined 15' degree and rolls to the bottom. The upper end of the ramp is 1.2 m higher than the lower end. What is the linear speed of the sphere when it reaches the bottom of the ramp? (Note: I=0.4MR^2 for a solid sphere and g=9.8 m/s^2)