# Vectors i/j

## Homework Statement

A motorist drives south at 24.0 m/s for 3.00 min, then turns west and travels at 25.0 m/s for 3.00 min, and finally travels northwest at 30.0 m/s for 1.00 min. For this 7.00 min trip, find the following values.
a. Total vector displacement displacement
b. Average speed
c. average velocity

## The Attempt at a Solution

a. Δr=24m/s(180s)south+25m/s(180s)west+30m/s(60s)north west

=4320m(-j)+4500m(-i)+1272.8(-i)+1272.8j Would this "j" be positive or negative?
=-5772.8i-3047.208

square root ((-5772.8)^2+(-3047.208)^2)=6527.680

θ=tan-1(3047.208/5772.8) or would it be tan-1(3047.208/5772.8)
=27

b. average speed=4320+4500+1800
1062/7(1/60)=
25.286

c. Would the average velocity direction be the same as the one from part a?

Thank you very much

Related Introductory Physics Homework Help News on Phys.org
a. yes you got it correct. that j should be positive since he is going north at that moment.
b. the average speed is also correct. another quicker way to get it is a weighted mean of the 3 speed.
c. yes the direction should be that of a. it means the total displacement per over total time.

Thank you very much

Regards