Question

You are walking on a long bridge. When you look in front of you, why does
the bridge seem to become narrow? And where does the bridge vanish?​

Answer 1

Answer: I was walking on a long bridge. When I look in front of me, the bridge seem to become narrow because of the large distance and the angular field.

The more I step back from the bridge, the more it becomes small and eventually vanishes. Example: the size of the sun and moon is very large but they look smaller on the earth due to the long distance.

Answer 2

The bridge looks narrow due to the long length and the aspect of angular view.  

Explanation:

• When I walk on a bridge it appears to be narrow in the front and this is due to the length of the bridge and the angular field of vision that we have.
• Gradually it appears as if the bridge has vanished in the far distance and this is because the two sides of the bridge have converged and then it exists as a point and eventually it appears to have vanished.