Newton contributed to astronomy by:

using mathematical reasoning
developing theories of gravity and motion
conducting systematic, structured experiments
all of the above

Newton contributed to astronomy by developing theories of gravity and motion.

Explanation:

Newton reflected on the fact that bodies weighed on Earth and that the stars revolved around other stars. He imagined that there was a universal force that caused bodies to attract each other. Newton called it "Universal Gravitation Force" or "Gravity."

Then, the force of gravity is the physical force exerted by the mass of a planet on the objects that are within its gravitational field. In other words, this law establishes that bodies, by simply having mass, experience a force of attraction to other bodies with mass.

Objects are attracted according to their mass and the distance between their centers: if the distance increases, the force decreases, and if the mass increases, the Universal Gravitation Force is more intense:

where G is the universal gravitation constant, whose value is

This expression indicates that the gravitational force that a point mass M exerts on another point mass m that is at a distance r from the previous one is directly proportional to the product of the masses and inversely proportional to the square of the distances that separates them.

answer: any goods being imported from another country may be subject to issued by the federal government are tariffs

explanation:  

tariffs are a tax on anything that are imported from abroad. government use them to protect and boost their local industries and the thought is that they encourage consumers to buy local instead of importing and they will hope will protect jobs and economy in the country that implements them  

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter