Final answer:
The radial acceleration of a car taking a freeway exit curve with a radius of 30 m at the posted speed limit of 17.5 m/s is calculated using the centripetal acceleration formula to be 10.2 m/s².
Step-by-step explanation:
To find the radial acceleration when the student takes the freeway exit at the posted speed limit, we use the formula for centripetal acceleration, which is a = v^2 / r, where v is the velocity and r is the radius of the curve.
Given the speed limit as 17.5 m/s and the radius of the curve as 30 m, we plug the values into the formula:
a = (17.5 m/s)^2 / 30 m
a = 306.25 m^2/s^2 / 30 m
a = 10.208 m/s^2
So, the radial acceleration of the car taking the exit at the posted speed is 10.2 m/s².