Answer
(a) The speed is $5.0~m/s$ when the stopwatch reads $12.0~s$
(b) The car moves 6.0 meters.
Work Step by Step
(a) We can find the velocity at $t= 12.0~s$:
$v_f = v_0+a~\Delta t$
$v_f = 1.0~m/s+(2.0~m/s^2)(2.0~s)$
$v_f = 5.0~m/s$
The speed is $5.0~m/s$ when the stopwatch reads $12.0~s$
(b) We can find the distance the car moves:
$\Delta x = v_0~t+\frac{1}{2}a(\Delta t)^2$
$\Delta x = (1.0~m/s)(2.0~s)+\frac{1}{2}(2.0~m/s^2)(2.0~s)^2$
$\Delta x = 6.0~m$
The car moves 6.0 meters.
