Rain is falling vertically. A man running on the road keeps his umbrella tilted but a man standing on the street keeps his umbrella vertical to protect himself from the rain. But both of them keep their umbrella vertical to avoid the vertical sun-rays. Explain.

Question

Philoid · Accepted Answer

Let us visualize this practical scenario using vector diagrams.

Man running will have greater velocity than the rain falling; both velocities are with respect to the street. Therefore, the resultant velocity is of rain with respect to the running man. The figure depicting this is shown below

Man standing with umbrella in the vertical falling rain is shown below

Now, velocity of man running is much less than the velocity of sun rays falling vertically.Therefore, the resultant velocity is in the same direction of the vertical sunrays. This is depicted in the figure below

Now, man standing with umbrella in a vertical falling sun rays is shown below