“Physical abuse is physical aggression directed at a child by an adult. It can involve striking, kicking, shoving, slapping, burning, bruising, pulling ears or hair, choking or shaking a child. Shaking a child can cause shaken baby syndrome, which can lead to intracranial pressure, swelling of the brain, diffuse axonal injury, and oxygen deprivation; which leads to patterns such as failure to thrive, vomiting, lethargy, seizures, bulging or tense fontanels, altered breathing, and dilated pupils. The transmission of toxins to a child through its mother (such as with fetal alcohol syndrome) can also be considered physical abuse in some jurisdictions.Most nations with child-abuse laws consider the infliction of physical injuries or actions that place the child in obvious risk of serious injury or death to be illegal.”
So, I guess the message is clear. If you see any of that going on to a child, then you need to intervene. In fact, I think there are laws that hold you accountable for not intervening when you see it happening and were able too do something about it.