Answer the following questions in detail.
What is distance–time graph? What is the nature of the distance–time graph of a body in the following cases? Represent graphically.
The body is moving with constant speed

Identify the biological process in our body that is nearly periodic and that can be used to measure time. 

Sometimes while driving, we see a board on the road that says ‘School Ahead'. What is the board actually trying to tell you to do?

The picture given here is the speedometer console of a sports car. What is the speed of the car (in $\mathrm{m}/\mathrm{h}$)? (Answer in numbers).

Speedometer gives us the information on the speed with which the vehicle is moving. Find out how the speedometer measures the speed of the vehicle when it is moving.

The figures given below show some vehicles moving on a road in the same direction.
Position of vehicles at 9:00 a.m.

Position of the vehicles at 9:02

Enter the distances covered in 2 minutes by the vehicles in the given table.

Plot a distance-time graph for the data in the space provided.