Can you help me answer these two please 2.How did astronomers figure out that the earth is round

An engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

Awalk up the phase change graph worksheet

How many neutrons does element x if it’s atomic number is 28 and its mass number is 87