## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

(a) We can find the vertical height $y$ that an object in freefall drops in 4.0 seconds. $y = \frac{1}{2}a_y~t^2$ $y = \frac{1}{2}(9.80~m/s^2)(4.0~s)^2$ $y = 78~m$ The tower should be 78 meters high. (b) We can find the impact velocity $v_y$. $v_y = v_{y0}+a_y~t$ $v_y = 0 + a_y~t$ $v_y = (9.80~m/s^2)(4.0~s)$ $v = 39~m/s$ The impact velocity is 39 m/s