Position, velocity, and acceleration vectors

[riafran]

Homework Statement

A motorist drives south at 20m/s for 3min, then turns west and travels at 25m/s for 2min, and finally travels northwest at 30m/s for 1min. For this 6min trip, find:
a) the total vector displacement
b) the average speed
c) average velocity

let the positive x-axis point east

Homework Equations

Vs = d/delta t
Vave= delta x/delta t

The Attempt at a Solution

i converted the mins to seconds, getting

south = 3600m
west = 3000m
northwest = 1800m

im getting confused because displacement is not the same as distance so i can't just add all 3 values together

for average speed i for 8400/6min = 23.3m/s

and I am not sure how to find the change in x for average velocity..

please help! thank you! =]

 

[LowlyPion]

Homework Statement

A motorist drives south at 20m/s for 3min, then turns west and travels at 25m/s for 2min, and finally travels northwest at 30m/s for 1min. For this 6min trip, find:
a) the total vector displacement
b) the average speed
c) average velocity

let the positive x-axis point east

Homework Equations

Vs = d/delta t
Vave= delta x/delta t

The Attempt at a Solution

i converted the mins to seconds, getting

south = 3600m
west = 3000m
northwest = 1800m

im getting confused because displacement is not the same as distance so i can't just add all 3 values together

for average speed i for 8400/6min = 23.3m/s

and I am not sure how to find the change in x for average velocity..

please help! thank you! =]

You found the speed. But Velocity is a vector. So is displacement.
Its magnitude is Displacement divided by the scalar Time.
So the average for the trip will be the total displacement divided by 360s.