Calculate the final velocity of the box after it reaches point C

This problem requires using the Work-Energy Theorem, which states that the work done by non-conservative forces ($W_{nc}$) equals the change in mechanical energy ($\Delta E$).

$$W_{nc} = \Delta E = E_{final} - E_{initial}$$

Where mechanical energy $E = KE + PE = \frac{1}{2}mv^2 + mgh$.

From the previous steps and the diagram:

• Mass of the box $m = 30 \text{ kg}$.
• Acceleration due to gravity $g = 9.8 \text{ m/s}^2$.
• At point A: $h_A = 5 \text{ m}$, $v_