What is the thing on the train that carries coal called?

Answer 1

A Hopper.

A hopper car is a type of railroad freight car used to transport loose bulk commodities such as coal, ore, grain,track ballast, and the like. The name originated from the coke manufacturing industry which is part of the steel industry This type of car is distinguished from agondola car in that it has opening doors on the underside or on the sides to discharge its cargo. The development of the hopper car went along with the development of automated handling of such commodities, with automated loading and unloading facilities. There are two main types of hopper car: open and covered.

Covered hopper cars are used for bulk cargo that must be protected from the elements (chiefly rain) such as grain, sugar, and fertilizer. Open cars are used for commodities such as coal, which can get wet and dry out with less harmful effect. Hopper cars have been used by railways worldwide whenever automated cargo handling has been desired.