Gravity
“Deliver those who are drawn toward death, And hold back those stumbling toward slaughter.” Proverbs 24:11
Gravitational force: every object in the universe that has mass exerts
a gravitation pull or force on every other mass.
The size of the pull depends on the masses of the objects. It also
pulls from the object's center of mass. We observe gravity because
the very large mass of the earth pulls on us and everything else that
is much less mass.
Example: When you drop your pencil, you mass is much greater
than that of the pencil, but the earth's mass is MUCH greater than
yours, so the pencil falls to the floor.
The gravitational force between the earth and the molecules of gas in the atmosphere is strong
enough to hold the atmosphere close to our surface. Smaller planets that have less mass may not be
able to hold an atmosphere.
The sun's gravitational pull keeps our planet orbiting the sun.
The moon's gravity pulls on the earth and makes the tides rise and fall every day. As the moon
passes over the ocean, there is a swell in sea level. As the earth rotates, the moon passes over new
parts of the earth, causing the swell to move also.
Gravitational acceleration = 9.8 m/s². This value applies to all objects regardless of mass. In the
absence of air resistance, all objects fall to earth at 9.8 m/s².
Why doesn't the moon fall toward the earth if earth's gravity is so strong? The moon IS falling all
the time: it would continue in a straight line path due to inertia, but it falls from that straight line
into a curve/orbit because of earth's gravity.