Question

For his daily training, an athlete runs a round a 15.0 m radius track five times in 2.50 minutes. What is his average speed? and average velocity?

Answer 1

Answer on Question #48013, Physics, Mechanics | Kinematics | Dynamics

Question:

For his daily training, an athlete runs a round a 15.0 m radius track five times in 2.50 minutes. What is his average speed? and average velocity?

Answer:

Velocity is a vector, having both a direction and a magnitude. Average velocity equals:

$$|\overrightarrow{v_a}| = \frac{\text{displacement}}{\text{time}}$$

For complete lap displacement equals 0. Therefore average velocity equals:

$$|\overrightarrow{v_a}| = \frac{0}{t} = 0$$

Average speed equals:

$$v_a = \frac{\text{total distance}}{\text{total time}} = \frac{5 \cdot 2 \cdot \pi \cdot 15 \, \text{m}}{170 \, \text{s}} = 2.77 \, \frac{\text{m}}{\text{s}}$$

Answer: average speed = 2.77 m/s, average velocity = 0 m/s

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