Final answer:
The acceleration of a car that slows down from 30m/s to 15m/s over 3 seconds is -5 m/s², indicating it is decelerating.
Step-by-step explanation:
The student asked for the acceleration of a car that slows down from 30m/s to 15m/s over a time interval of 3 seconds. Acceleration is defined as the change in velocity per unit of time. In this case, the change in velocity (∆v) is 15m/s - 30m/s, which gives us -15m/s (the negative sign indicates deceleration). The time interval (∆t) is 3 seconds. Using the formula for acceleration (a = ∆v / ∆t), we can calculate the acceleration as follows:
a = ∆v / ∆t = (-15m/s) / (3s) = -5m/s².
Therefore, the acceleration of the car is -5 meters per second squared (m/s²), which indicates that the car is decelerating.