Question

When a 1984 Alfa Romeo Spider sports car accelerates in the x-direction at the maximum possible rate, its motion during the first 20. seconds is extremely well modeled by the simple equation vx 2 = (60 m2 /s3 )t, where t is time in seconds and vx is in m/s. In other words, the square of the car's velocity increases linearly with time. What is its acceleration after 3s, assuming that the car starts from rest at t = 0 s?

The answer is 2.2 but I need to know how to do it

Answer 1