When the volume increased, what happened to the density?

An inclined plane wrapped around a metal shaft is a a. lever b. screw c. pulley d. wedge

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?

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?