An amateur astronomer grinds a double convex lens whose surfaces have radii of curvature of 40 cm and 60 cm. The glass has an index of refraction of 1.54. What is the focal length of this lens in air?

Aboat travels at 15 m/s in a direction 45° east of north. the boat then turns and travels at 18 m/s in a direction 5° north of east. what is the magnitude of the boat's resultant velocity? round your answer to the nearest whole number. /s what is the direction of the boat's resultant velocity? round your answer to the nearest whole degree. ° north of east