Until a train is a safe distance from the station, it must travel at 5 m/s. Once the train is on open track, it can speed up to 45 m/s. If it takes a train 8 seconds to reach 45 m/s, what is the acceleration of the train?

In a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina. what should be the radius of curvature of the cornea such that the image of an object 40.0 cm from the cornea’s vertex is focused on the retina?