What will be the velocity of a train if it covers the distance of 30m in 3 s?

Asystematic approach to problem solving is called a (an)

Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)

What is the orbital period of a spacecraft in a low orbit near the surface of mars? the radius of mars is 3.4×106m.