Can the displacement of a particle be zero when the distance travelled is not zero?

In a long distance race,the athletes were expected to take four rounds of the track such that the finish line was the same as the start line. Suppose the length of the track was $200 \ m$.
$(a)$ What is the total distance to be covered by the athletes?
$(b)$ What is the displacement of the athletes when they touch the finish line?
$(c)$ Is the motion of the athletes uniform or nonuniform?
$(d)$ Is the displacement of an athlete and the distance moved by him at the end of the race equal?

Can a body have constant speed and still be accelerating?

The slope of a velocity-time graph gives:

What kind of motion of a body is represented by the graphs given below?

If the displacement of an object is proportional to the square of time,then the object moves with