Which of these actions is an example of circular motion?

Three students start running from the starting point at the same time. The picture shows the position of the students on the path after a minute. Which student ran the fastest? Explain your answer.

The diagram shows a pendulum in periodic motion. The time period of a pendulum is the time taken by the bob to make one complete oscillation. 

What would be the movement of the bob for one complete oscillation of the pendulum?

The table shows the time taken for $30$ oscillations by four different pendulums.

Which pendulum has the shortest time period?

Anju walks $8 \mathrm{m}$ to the east, then $6 \mathrm{m}$ to the south, then $8 \mathrm{m}$ to the west, and finally $6 \mathrm{m}$ to the north. What is the distance covered and displacement of Anju?

The diagram shows a strip of paper tape that has been pulled under a vibrating arm by an object moving at constant speed. The arm is moving regularly, making $50$ dots per second.

What was the speed of the object? 

Suppose the two photographs, shown in Fig.1 and Fig. 2, had been taken at an interval of $10 \mathrm{seconds}$. If a distance of $100 \mathrm{m}$ is shown by $1 \mathrm{cm}$ in these photographs, calculate the speed of the blue car.