## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

$a = 0$ $v = 4~m/s$
We can find the acceleration from t = 0 to t = 3 s: $a = \frac{F}{m}$ $a = \frac{4.0~N}{2.0~kg}$ $a = 2.0~m/s^2$ We can find the acceleration from t = 3 s to t = 5 s: $a = \frac{F}{m}$ $a = \frac{-2.0~N}{2.0~kg}$ $a = -1.0~m/s^2$ We can find the acceleration from t = 5 s to t = 7 s: $a = \frac{F}{m}$ $a = \frac{0}{2.0~kg}$ $a = 0$ At t = 6 s: Since the force on the object is zero, the acceleration is also zero. We can find the velocity at t = 3 s: $v = a~t = (2.0~m/s^2)(3~s) = 6~m/s$ We can find the velocity at t = 5 s. We can let $v_0=6~m/s$ for this part of the question. $v = v_0+ a~t$ $v = (6~m/s)+ (-1.0~m/s^2)(2~s) = 4~m/s$ Since the object does not accelerate after t = 5 s, the velocity at t = 6 s is $4~m/s$.