Do You Know?

1. After completing a long run (like the Citizen's Run in Chennai or a half-marathon), a runner's legs feel stiffer two days after the event than the following day. Why does this happen?
2. What is the maximum length of a straw or tube with which you can suck juice or water out of a glass?
3. Why is it colder at the South pole than at the North pole?
4. If you wake up early in the morning, you will often find heavy water droplets on the tips of leaves and grass. How do they get there?
5. The tyres of vehicles are not smooth but have many zig-zag cuts and patterns on them. Why?