1. **Problem:** A volleyball with mass 240 g is thrown downward from a height of 10 m with an initial velocity of 2.5 m/s. Given gravitational acceleration $g=10$ m/s², find the kinetic energy at a height of 3 m. 2. **Formula:** Kinetic energy at height $h$ is given by $$E_k = \frac{1}{2} m v^2$$ where $v$ is the velocity at height $h$. 3. **Step 1: Convert mass to kg** $$m = 240\text{ g} = 0.24\text{ kg}$$ 4. **Step 2: Use conservation of energy or kinematic equations to find velocity at 3 m** Initial height $h_0 = 10$ m, final height $h = 3$ m, initial velocity $v_0 = 2.5$ m/s downward. 5. **Step 3: Calculate velocity at 3 m using kinematic equation** $$v^2 = v_0^2 + 2g(h_0 - h)$$ $$v^2 = (2.5)^2 + 2 \times 10 \times (10 - 3) = 6.25 + 140 = 146.25$$ $$v = \sqrt{146.25} \approx 12.09\text{ m/s}$$ 6. **Step 4: Calculate kinetic energy at 3 m** $$E_k = \frac{1}{2} \times 0.24 \times (12.09)^2 = 0.12 \times 146.25 = 17.55\text{ J}$$ **Final answer:** The kinetic energy at 3 m height is approximately **17.55 J**.