Gravity means the force that attracts a body toward the center of the earth, or toward any other physical body having mass. For most purposes Newton's laws of gravity apply, with minor modifications to take the general theory of relativity into account.
Think of it like this
Internal: A force inside yourself
External: A force outside of yourself
So if there an external force, it’s a force from outside so an example would be bullying. You wouldn’t want to go where you are being bullied so that would be an outside force affecting you.
So that you don't drift off from the topic and to make it nice and simple
Possibly it depends on how good their eye sight is in the one eye i mean if a cyclops can do it then he should be able to
Greg gets along better with other people at the end of the story because he leans a valuable lesson from fighting the thugs with Lemon Brown.