\[ mg = ma \]

\[ a = g \]

• سرعة الجسم.
• شكل الجسم ومساحة مقطعه.
• كثافة المائعالذي يتحرك فيه الجسم.

\[ t_{up} = \frac{3.4}{2} = 1.7 \, \mathrm{s} \]

\[ 0 = u - 10 \times 1.7 \implies u = 17 \, \mathrm{m/s} \]

\[ s_{max} = \frac{17+0}{2} \times 1.7 = 8.5 \times 1.7 = 14.45 \, \mathrm{m} \]

\[ 0^2 = 17^2 - 2(10)s \implies 20s = 289 \implies s = 14.45 \, \mathrm{m} \]

\[ R = k v^2 \]

\[ R_{\text{new}} = k (v_{\text{new}})^2 = k \left(\frac{v}{4}\right)^2 = k \left(\frac{v^2}{16}\right) = \frac{1}{16} (k v^2) \]

\[ R_{\text{new}} = \frac{1}{16} R \]