Answer
$a=3\frac{5}{9}m/s^{2}$
Work Step by Step
We first convert km/hr into meters per second:
$56.0km/h\times\frac{1000m}{1km}\times\frac{1h}{3600s}=15\frac{5}{9}m/s$
We now use this value and other known values to solve:
$d=v_{0}t+\frac{1}{2}at^{2}$
$d-v_{0}t=\frac{1}{2}at^{2}$
$a=2(d-v_{0}t)/t^{2}$
$a=2[(24.0m)-(15\frac{5}{9}m/s)(2.00s)]/(2.00s)^{2}=-3\frac{5}{9}m/s^{2}$
Magnitude: $3\frac{5}{9}m/s^{2}$
