# Need Avg. Velocity Equation

1. Oct 3, 2007

### mkylman

1. The problem statement, all variables and given/known data

You ride your bike for 1.5h @ avg velocity of 10km/h, then for 30min @ 15km/h
What is you average velocity?

So I think that the variables are this

Vf=15km/h(.000004m/s)
Vi=10km/h(.000003m/s)
Tf=90m(5400s)
Tf=30m(1800s)

2. Relevant equations

I think that it is
Code (Text):
V[sub]avg[/sub] = d[sub]f[/sub] - d[sub]i[/sub]
------
t[sub]f[/sub] - t[sub]i[/sub]

3. The attempt at a solution

everything I try I get gross decimal numbers -_- Isn't there an easier way???

Last edited: Oct 3, 2007
2. Oct 3, 2007

### Dick

0.000004m/sec is nothing like 15km/hr. I hope you are not using that. Just work in km and hr. You got the right equation though. How far did you travel in all and how long did it take you in all? The quotient is the average velocity.

3. Oct 3, 2007

### mkylman

so to get the total distance I'd have to do

d = t/v

1.5h/10kmh = 15km
.5h/15kmh = 7.5km
overall d = 22.5km
overall t = 2h

so my average velocity is
Code (Text):

v = d/t
v = 22.5km/h
--------
2h
v = 11.25km/h
^ that???

Last edited: Oct 3, 2007
4. Oct 3, 2007

### Dick

^ That!!! But I've never seen anyone write / for multiplication before. Don't you mean like 1.5hr*10km/hr=15km?

5. Oct 3, 2007

### mkylman

yeah my bad -_- I hadn't realized it til afterwards; I have no idea what I was typing ^_^

Thank you so much man!