Question

an athlete runs 300 m up a hill at a steady speed of 3.0 m/s. She then immediately runs the same distance at 6.0 m/s . What is her average speed for 600 m run?

Answer 1

Answer:

4.0 m/s

Explanation:

In the first part of the run, the athlete runs a distance of

$d_1 = 300 m$

at a speed of

$v_1 = 3.0 m/s$

So, the time he/she takes is

$t_1 = \frac{d_1}{v_1}=\frac{300}{3.0}=100 s$

In the second part of the run, the athlete covers an additional distance of

$d_2 = 300 m$

with a speed

$v_2 = 6.0 m/s$

So, the time taken in this second part is

$t_2 = \frac{d_2}{v_2}=\frac{300}{6.0}=50 s$

So, the total distance covered is

d = 300 m + 300 m = 600 m

And the total time taken

t = 100 s + 50 s = 150 s

Therefore, the average speed for the entire trip is

$v=\frac{d}{t}=\frac{600}{150}=4.0 m/s$