Answer: acceleration = -1.68 m/s^2
Explanation: First, you need to convert the speeds to meters per second (m/s) since acceleration is typically measured in m/s^2.
2.0 km/hr = 0.56 m/s
0.5 km/hr = 0.14 m/s
Next, you use the formula for acceleration: acceleration = (final velocity - initial velocity) / time
Plugging in the values, we get: acceleration = (0.14 m/s - 0.56 m/s) / 0.25 hr
acceleration = (-0.42 m/s) / 0.25 hr
acceleration = -1.68 m/s^2