Consider jumping on a trampoline. You move a lot and so does the trampoline.
Jumping on the floor you move the floor not.
Consider the Moon going round the earth. The earth’s gravity keeps the moon going round while the moons gravity has noticeable effects on the earth like causing tides.
However take a man made satellite going round the earth. The earth is able to move it round and round, but the satellite will hardly ever effect the earth.
So if one body is of a much greater mass than another then you have an unmoved mover.
Suppose something was of infinite mass then anything of finite mass would be moved by it but itself will be unmoved.
Jumping on the floor you move the floor not.
Consider the Moon going round the earth. The earth’s gravity keeps the moon going round while the moons gravity has noticeable effects on the earth like causing tides.
However take a man made satellite going round the earth. The earth is able to move it round and round, but the satellite will hardly ever effect the earth.
So if one body is of a much greater mass than another then you have an unmoved mover.
Suppose something was of infinite mass then anything of finite mass would be moved by it but itself will be unmoved.
