Why does the driver of a vehicle wipe the glass inside, even if the wiper is working on the outer surface of the glass. When he drives in rain?

Why do we see water droplets on outer surface of a glass containing ice cold water ?

Why water droplets wet the glass surface and does not wet lotus leaf?

Why does a person standing for a long time get tired when he does not appear to be doing any work ?

Explain why Water on a clean glass surface tends to spread out while mercury on the same surface tends to form drops. (Put differently ,water wets glass while mercury does not).

You may have seen in a circus a motorcyclist driving in vertical loops inside a ‘death- well’ (a hollow spherical chamber with holes, so the spectators can watch from outside). Explain clearly why the motorcyclist does not drop down when he is at the uppermost point, with no support from below. What is the minimum speed required at the uppermost position to perform a vertical loop if the radius of the chamber is 25 m ?