Final answer:
The car's acceleration is calculated using the change in velocity divided by the time taken. After converting the time from seconds to hours, the acceleration is found to be 43200 km/h².
Step-by-step explanation:
To calculate the car's acceleration in km/h², we can use the formula: acceleration = (final velocity - initial velocity) / time. Here, the final velocity is 90 km/h, the initial velocity is 0 km/h, as it is starting from rest, and the time is 7.5 seconds. To convert the acceleration into km/h², we first convert 7.5 seconds into hours (7.5/3600 hours) and then apply the formula.
Acceleration = (90 km/h - 0 km/h) / (7.5 / 3600 hours) = 43200 km/h². Therefore, the car's acceleration is 43200 km/h².
This calculation shows how quickly the car is able to increase its speed, which is an important aspect when evaluating the performance of the vehicle.