As “modern” America developed between 1919 and 1945, what political, social, or economic aspects of the country changed OR stayed the same? (Give at least two examples to support your answer)?

What important discovery was made by edmond halley and alexis clairaut, using newton's ideas of mathematics and gravity? they created the scientific method to outline how science should be conducted. they were able to find the orbit of a comet and predict the year of its return. they discovered the three newest planets--uranus, neptune, and pluto. they explained why objects appear to have color.