A skateboarder starts from the origin of a straight track

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A skateboarder starts from the origin of a straight track. • He moves away from the origin with constant velocity

2\,\text{m/s}

for

3\,\text{s}

. • He then rests completely for

2\,\text{s}

. • After resting, he returns toward the origin with constant velocity

3\,\text{m/s}

for

4\,\text{s}

and comes to rest. Taking motion away from the origin as the positive direction, answer the following: (i) Draw a displacement–time graph for the entire

9\,\text{s}

motion and mark all key points. (ii) Using the same time scale on a separate set of axes, draw the corresponding velocity–time graph. (iii) From the velocity–time graph, calculate (a) the total distance travelled and (b) the average velocity for the whole journey. (iv) State why part of the velocity–time graph lies below the time axis and relate this to the skateboarder’s motion.

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