What is the difference between mass and weight? Weight is the observed effect of gravity on mass.
Mass is how much; weight is how much space.
Weight is how much; mass is how much space.
Weight and mass are the same everywhere.
Mass is the observed effect of inertia on weight.

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.