Answer 1

Strong:

The child object depends of the parent object's lifetime. Simple words: "it's part of it".

Example: A wheel class inherits from a car class, if the Car class disappears, the wheel class will disappear (or it should to) too, because the wheel one, because it depends directly of the car class to work.

Weak:

The child object doesn't depend directly of the parent obejct's lifetime.

Example: I have my lunch class which inherits from a break class, if I don't take my lunch, nothing else happens, both classes lifetime will keep going work.

Those were some weird examples, bit that's what I can remember for now. I hope it helps you.

P.S: If I'm wrong, please tell me and dislike this comment. I will correct it if it is.

(Sorry for my bad english)