What is the displacement of the Earth when it completes one revolution around the Sun?

Distinguish between the scalar quantity and vector quantity.

On a $100 \mathrm{m}$ straight track, an athlete completes the race from the starting line up to the final in a particular time. Calculate the magnitude of displacement.

A rectangular track is $40 \mathrm{m}$ long and $30 \mathrm{m}$ broad. A man starts walking from one corner of the track and reaches the opposite corner. Find the distance travelled and the magnitude of displacement.