*physical science not physics* *40 pts*
why do scientists build models?
a. to make generalizations about natural phenomena.
b. the observed behavior may represent the universe as a whole
c. the universe is big and complex so it may be to create a smaller physical system to study
d. all of the above

Niobium forms a substitutional solid solution with vanadium. compute the number of niobium atoms per cubic centimeter for a niobium-vanadium alloy that contains 24 wt% nb and 76 wt% v. the densities of pure niobium and vanadium are 8.57 and 6.10 g/cm3, respectively

Astudent is given an assignment to demonstrate diffraction. he takes a photograph of a straw in a glass of water. the straw appears bent at the water level. which best describes this example? a) this is a good example of diffraction. b) this is an example of dispersion and not diffraction. c) this is an example of refraction and not diffraction. d) this is an example of reflection and not diffraction.

Question 11 of 13 (1 point) jump to question: a stairway, ladder, or ramp must be present in excavations in which of the following situations? a. all trenches must have access/egress b. the trench is more than 15 feet wide but only 1 ½ feet deep c. the trench is more than 4 feet deep and the devices must be within 25 feet of all workers