To calculate the car's acceleration in kilometers per hour per second, we need to convert the units appropriately to have consistent units for time and velocity.
Given: Initial velocity (u) = 98 kilometers per hour Final velocity (v) = 0 kilometers per hour Time (t) = 15 seconds
First, let's convert the initial velocity from kilometers per hour to meters per second since the SI unit for acceleration is meters per second squared (m/s²).
1 kilometer = 1000 meters 1 hour = 3600 seconds
98 kilometers per hour = (98 × 1000 meters) / (1 hour) = 98,000 meters / 3600 seconds ≈ 27.22 meters per second (m/s)
Now, we can calculate the acceleration using the formula:
Acceleration (a) = (Final velocity - Initial velocity) / Time
Acceleration (a) = (0 m/s - 27.22 m/s) / 15 seconds Acceleration (a) = -27.22 m/s / 15 seconds Acceleration (a) ≈ -1.81 m/s²
Finally, let's convert the acceleration from meters per second squared (m/s²) to kilometers per hour per second (km/h/s).
1 meter per second = 3.6 kilometers per hour
Acceleration (a) ≈ -1.81 m/s² × 3.6 km/h = -6.52 km/h/s
Therefore, the car's acceleration is approximately -6.52 kilometers per hour per second. The negative sign indicates that the car is decelerating or slowing down.