Question

(c) When the train crossed a river, it made a different sound. Why​

Answer 1

Answer:Because the gap of bridge and river

Explanation:

Answer 2

Answer:

Ballast is a coarse-grained, gravel-like substance made of shattered stone that is used to lay the railway on land.

Explanation:

due to the river's and bridge's gap

Reasons are:

• Ballast is a poorly graded, gravel-like substance produced of shattered stone that is used to lay the railway on land. Bridge tracks are firmly connected to a robust steel framework. The hard framework will be excited by the train's vibrations, which will intensify the sound.
• Because the train was on a bridge and there was no earth present, only rails, and water, the sound of the driving train abruptly altered.
• The sound is produced as a result of the wheels' lateral movement and subsequent contact with and friction with the tracks. Train noise is the sound that trains make when they move.
• The train's many components, including the engines, traction motors, brakes, and the wheels spinning on the tracks, all produce a variety of different noises. Noise and vibration are caused by roughness and imperfections on the surfaces of the wheels and rails.