We are given that a car travels in circular motion is a semi-circle of radius 291 m and longitude of 915 m. To determine the centripetal acceleration we will use the following formula for the centripetal acceleration in a circular motion:

Where:

To determine the velocity we will use the fact that the car travels at a constant speed, therefore, the velocity is the quotient of the longitude of the track and the time it takes the car to travel through it:

Where:

Now we plug in the values:

Solving the operations we get:

Now we use this value in the formula for the acceleration:

Now we solve the operations and we get:

Therefore, the centripetal acceleration of the car is 12.79 meters per second squared.