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# Now, for the main questions, consider a baseball that is thrown straight upward from the roof of a 100 meter high building. It hits the street below eight seconds later. Question 1 6 pts Let $s(t)$ be the distance between the ball and the ground $t$ seconds after the ball is thrown upward. If we assume the only force acting on the ball is the force of gravity, which of the following set of data describes the motion of the ball? $\left\{\begin{array}{l} \frac{d^{2} s}{d t^{2}}=9.8 \\ s(0)=100 \\ s^{\prime}(0)=0 \end{array}\right.$ $\left\{\begin{array}{l}\frac{d^{2} s}{d t^{2}}=-9.8 \\ s(0)=100 \\ s(8)=0\end{array}\right.$ $\left\{\begin{array}{l}\frac{d^{2} s}{d t^{2}}=9.8 \\ s(0)=100\end{array}\right.$$\left\{\begin{array}{l} \frac{d^{2} s}{d t^{2}}=9.8 \\ s(0)=100 \\ s(8)=0 \end{array}\right.$ Question 2 $6 \mathrm{pts}$ What is the initial velocity of the ball? $-26.7 \mathrm{~m} / \mathrm{s}$ $0 \mathrm{~m} / \mathrm{s}$ $26.7 \mathrm{~m} / \mathrm{s}$ $51.7 \mathrm{~m} / \mathrm{s}$ $-51.7 \mathrm{~m} / \mathrm{s}$Question 3 8 pts If $v_{0}$ denotes the initial velocity of the ball, which of the following expressions described how high the ball rose? $s\left(v_{0} / 9.8\right)$ $s\left(-v_{0} / 9.8\right)$ $s\left(v_{0} / 4.9\right)$ $s\left(-v_{0} / 4.9\right)$  