What causes baseballs to travel farther in Denver?

Denver Skyline Photo Courtesy HHS

Denver is the highest city that is home to a Major League Baseball team. Denver is called the Mile-High City because it is about one mile above sea level. That means there are two possible reasons that baseballs travel farther in Denver:

• the farther away you move from the center of Earth, the less gravity there is
• the higher you climb in Earth's atmosphere the less air there is.

Gravity - All objects with mass pull on all other objects with mass. The greater the mass of an object, the stronger its pull. Objects as small as an atom or as large as a galaxy exert this pull known gravity.

The distance between two masses also affects the force of gravity. As a spacecraft moves away from Earth, the attraction between Earth and the spacecraft grows smaller and smaller. In fact, when the distance between the center of masses doubles the force of gravity is only one fourth as strong.

What is the difference between gravity at sea level and gravity in Denver?

Going from sea level to Denver changes the distance between a baseball and the center of the Earth by about 0.25 %. This means that gravity in Denver is 0.06 % lower than gravity at sea level. Another way of saying this is that the gravity in Denver is 99.94 % of sea level gravity.

Air - As a baseball moves through the air, it pushes aside the molecules in its path. But air molecules push back. The faster a ball moves the greater the resistance to its movement. But because Denver is a mile higher than sea level its air is less dense. That means there is less air that must be pushed aside.

How much less dense is the air in Denver?

As you climb higher in the atmosphere, density of the air falls. By the time you reach an altitude of one mile, air density is only 85.5% of sea level density.

Which do you think has a greater effect on home-run distance?

Is it the air or is it the gravity?