A block slides up a friction less, inclined plane with = 25 (Fig. P4.83). (a) If

A block slides up a friction less, inclined plane with θ = 25° (Fig. P4.83). 

(a) If the block reaches a maximum height h = 4.5 m, what was the initial speed of the lock? 

(b) Now consider a second inclined plane with the same tilt angle and for which the coefficient of kinetic friction between the block and the plane is µ_K = 0.15. What initial speed is now required for the block to reach the same maximum height?

Figure P4.83