In order to answer your question, we must first define what "crying" actually means.
Crying is the eyes' response to a certain emotional state, physical pain, or irritants. Crying is commonly caused by three emotions: happiness, sadness, anger.
Now with this, we can extrapolate that the reason one person may be crying because of another person is due to the fact that they have experienced something that caused their eyes to trigger a reaction which caused them to wet their eyes.
Most likely, this particular scenario is caused by a reaction to an emotional state, which means that there's a high likelihood that a person's eyes are reacting from emotion that they felt from that person.
maybe he has fractured his arm . you can go to the nearest hospital or clinic so they can check your grandfather
NO! there is no need for martial law because things will just get more complicated.