Rationale
The acceleration of the object is -1.5 m/s².
To calculate acceleration using the formula a = (V2 - V1)/t, we substitute V1 = 14 m/s, V2 = 8 m/s, and t = 4 s. The resulting calculation shows that the object is decelerating, resulting in a negative acceleration value.
A) An acceleration of 1.5 m/s² suggests that the object's speed is increasing over time. However, this scenario describes a decrease in speed, as V2 is less than V1, indicating that the calculation must yield a negative result, therefore rendering this option incorrect.
B) The calculation for acceleration using the values provided yields a = (8 m/s - 14 m/s) / 4 s = -6 m/s / 4 s = -1.5 m/s². This negative value accurately reflects the deceleration of the object, confirming that it is slowing down.
C) An acceleration of 4.5 m/s² indicates a significant increase in velocity, which contradicts the initial conditions where the object slows down from 14 m/s to 8 m/s. This value does not correspond to the correct application of the acceleration formula with the given velocities and time.
D) An acceleration of -12 m/s² implies an extremely high rate of deceleration, which is not supported by the velocity change over the given time. The calculation does not yield this value, as the correct calculation results in -1.5 m/s², making this choice incorrect.
Conclusion
Acceleration measures how quickly an object changes its velocity, and in this case, the object is decelerating as it moves from a higher initial velocity to a lower final velocity. The correct calculation yields an acceleration of -1.5 m/s², indicating a reduction in speed over the specified time period. Thus, understanding the sign and magnitude of acceleration is crucial for interpreting motion accurately.