India totally dominated the second half as the forwards shed off their markers and tore open the Belarus defence.
Poonam scored the second goal three minutes into the second half with a crisp volley past defender Kibkova and Mikanovich.
Ritu increased India's tally when she converted a penalty corner in the 51st minute.
Rani Devi then went on a goal-scoring spree, sounding the board thrice within a span of just six minutes.
Belarus substituted their goalkeeper bringing in Yauheniya Letsko, but it made no difference.
India will now play hosts USA in their last preliminary pool game Thursday.