A cyclist travels 60 metres north and then 80 metres south in 20 seconds. What is the magnitude of his average velocity?
One metre per second
Average velocity is a vector: it is total displacement divided by total time, not total distance divided by total time. Displacement is measured from the starting point to the final position, taking direction into account.
The cyclist first moves 60 m north and then 80 m south. Taking north as positive, the net displacement is 60 − 80 = −20 m, i.e. 20 m towards the south. The total time is 20 s, so the magnitude of the average velocity is 20 ⁄ 20 = 1 m/s. Zero would apply only if the cyclist returned to the start, seven and five m/s do not match the calculation.
Hence, the answer is One metre per second.
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Which of the following quantities specifies its speed with direction?
The basic unit of speed of an object is ______.
- Which of the following represents non-uniform linear velocity?
- Which of the following describes the nature of the average speed?
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