Jenny uses 2 cups of paint in 4 hours to paint a portrait. how many cups does she use in 30 minutes?

Average acceleration: i have no idea how to do this.

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

Answer! if you don’t mind, can you explain