일반물리학 1 — Potential Energy and Conservation of Energy: Problem 62

62 In Fig. 8-44, a block slides along a path that is without friction until the block reaches the section of length $L = 0.65\text{ m}$, which begins at height $h = 2.0\text{ m}$ on a ramp of angle $\theta = 30^\circ$. In that section, the coefficient of kinetic friction is $0.40$. The block passes through point $A$ with a speed of $8.0\text{ m/s}$. If the block can reach point $B$ (where the friction ends), what is its speed there, and if it cannot, what is its greatest height above $A$?