A small ball starts to fall from a standstill at a height of 18m. Suppose that the air resistance in the process of falling is always 0.1 times of gravity Find: (1) the acceleration of the ball (2) The speed of the ball when it lands

(1) Because g = 10m / s, the resistance is 0.1mg, so Ma = mg-0.1mg = 0.9mg, so a = 9m / S. (2) from the formula, 2aX = V ^ 2-0. SO 2 * 9 * 18 = V ^ 2-0. So v = 18m / s,

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