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

(a) $t = 2$ or $t=5$ (b) At t = 2 s: $a = -3~m/s^2$ At t = 5 s: $a = 3~m/s^2$
(a) $v(t) = t^2-7t+10$ We can find the turning points when $v(t) = 0$; $t^2-7t+10 = 0$ $(t-5)(t-2) = 0$ $t = 2$ or $t=5$ (b) $a(t) = \frac{dv}{dt} = 2t-7$ At t = 2 s: $a = (2)(2)-7$ $a = -3~m/s^2$ At t = 5 s: $a = (2)(5)-7$ $a = 3~m/s^2$