This certainly is a tough situation, and I totally agree with Twisterdog that you need to talk to someone in real life, someone who knows you and your family, or even not, just an actual human to human interaction.
It's so easy to come one here and vent about it, and it feels good--there's nothing wrong with it, we all would love to help. Unfortunately the best we can do is give advice, and it seems to me that you need more than that.

The man has serious problems. One day it's the clock, the next day it's your mother or you he's throwing against a wall. That's how the pattern of abuse forms. I've had the unfortunate experience of knowing too many people this has happened to (and 1 is 1 too many).

You and your mother need to get out of this situation. If she won't do that for you, than you need to get out yourself. Do you have any other family members you can stay with, or friends?? Do whatever you can to remove yourself from the situation.

If you cannot get out of this awful situation, please just do what he asks--I know how much you don't want to, because he is such a jerk, but for your own sake, just do what he says next time.

{{{{{hugs}}}}}}