When a soccer ball is kicked toward a player and the player deflects the ball by "heading" it, the acceleration of the head
during the collision can be significant. Figure $2-38$ gives the measured acccleration $a(t)$ of a soccer player's head for a bare head and a helmeted head, starting from rest. The scaling on the vertical axis is set by $a_{s}=200 \mathrm{~m} / \mathrm{s}^{2}$. At time $t=7,0 \mathrm{~ms}$, what is the difference in the speed acquired by the bare head and the speed acquired by the helmeted head?