Question

why is a bullet train streamlined

Answer 1

The streamlined shape of a high-speed bullet train helps decrease air resistance, allowing the train to travel more efficiently.

Answer 2

(1) A streamlined body: To achieve speeds of 200 kilometers per hour (130 miles per hour) and more, the trains needed to be as aerodynamic (to cause as little wind resistance) as possible. That is why the front cars of the Shinkansen trains are tapered like the nose of an airplane.
streamlined body helps the trains to maintain thrust on the ground otherwise they will fly