How does a physicist answer a scientific question?

Ingrid wrote the hypothesis below. if the temperature of a liquid increases, the density of the liquid decreases because the particles move farther apart. what are the variables in her hypothesis?

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?

Which of these is constant for all types of electromagnetic radiation in a vacuum? select one: a. wavelength b. frequency c. photon energy d. amplitude e. velocity