This is a great question. Physical abuse or any type of abuse for that matter is a horrible thing in our world. From a Christian point of view, we can say a few things.
First, Christianity has a strong doctrine of human depravity. So, a Christan worldview can explain why there are things like physical abuse in our world. People are fallen and they do at times things that are sinful.
Second, the Christian doctrine of sanctification can also be helpful in this discussion. Christianity states that people can change. So, a person who abuses another can learn to stop in view of God's grace. Ephesians 4:25-28 is a good example:
25 Therefore each of you must put off falsehood and speak truthfully to your neighbor, for we are all members of one body.26 “In your anger do not sin” Do not let the sun go down while you are still angry, 27 and do not give the devil a foothold.28 Anyone who has been stealing must steal no longer, but must work, doing something useful with their own hands, that they may have something to share with those in need.
Third, the person who is abused also has resources in Christianity. For example, Christianity speaks of inner healing, self esteem and even the idea of forgiveness.
In a word, Christianity can address physical abuse as well as the various other problems in our world.