Card with Physical attacks can attack only from 1st position in your team.  These cards will have the icon on the card. For e.g. Upchitr has a physical attack and can do a damage of 1 unit.

Abilities that affect Physical Attacks

Ajanubahu

Physical attack works from 2nd position

Kark

Attacks from anywhere; targets lowest Stamina card

Shankhnaad

Your cards with Physical attack will get increased attack

ShastrBhransh

Reduces damage from Physical and Ranged attacks

Pushpak

Dodges Physical and Ranged attacks

Ghatak

Attacks the last card in opponent’s team