For a diverging lens with one flat surface, the radius of curvature for the curved surface is 8 cm. what must the index of refraction be so that the focal length is -15 cm? a) 1.1632 b) 1.56 c) 1.35088 d) 1.18 e) 1.533

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )