Displacement and 1-D Kinematics

[Loppyfoot]

[SOLVED] Displacement and 1-D Kinematics

Homework Statement

A runner runs 15 km, in a straight line, in 20 min and then takes 45 min to walk back to the beginning. Find the average velocity for the whole trip.

Homework Equations

V_av= (X_f-X_i) / (t_f-t_i)

The Attempt at a Solution

Wouldn't the displacement be 0? If so; what is the average velocity of the whole trip? It couldn't be 0.

It would be 0. Silly me.

 

[CaptainEvil]

Where is this equation from?

Tackle the problem from two parts: find the speed of his run, and the speed of his walk, and average them.

You know S = d/t yes? So convert the time to hours, do the question in two steps and average.

 

[Loppyfoot]

Yup; thanks. I figured it out.