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

4.0 m/s

Step-by-step 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 = (d_1)/(v_1)=(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 = (d_2)/(v_2)=(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=(d)/(t)=(600)/(150)=4.0 m/s`