If you'r referring to some objects, it means that the mass of the object is less than the water so it floats. If the mass of an object is greater than the mass of the water, it will sink. Compare it to a balloon, helium makes it rise, while normal air makes it sink.
Light waves are reflected from front and back surfaces of the thin films and constructive interference between the two reflected waves occurs in different places for different wavelengths. Light shining on the upper surface of the thin film with thickness t is partly reflected at the upper surface (path abc). Light transmitted from the upper surface is partly reflected at the lower surface (path abdef). The two reflected waves come together at point P on the retina of the eye. Depending on the phase relationship, they may interfere constructively or destructively. Different colors have different wavelengths, so the interference may be constructive for some colors and destructive for others.
My guess for this one would be; 400 N
My reasoning would be; it starts at 0 on both X and Y, if you need to get to 1.00 meters thats 4/4. 1/4 of 1.00 is .25, and on .25 its on 100 so multiply it by 4 to make 1.00 and you get 400 N