# Another simple velocity question.

1. Oct 3, 2007

### cherryrocket

[SOLVED] Another simple velocity question.

"Juanita left on a walk 45 min ago. She is travelling at 4.5 km/h. How fast must you travel to catch up to her in 1.0h"?

Juanita t=45 min v=4.5 km/h
d=vt = (4.5km/h)(0.75h) = 3.375 km

Me -
v=d/t = (3.375km)/1.0h = 3.4 km/h

I must travel at 3.4 km/h to catch up to her in 1 hour.
Correct?

2. Oct 3, 2007

### Sourabh N

for the 1 hour you chased Jua... she must also have traveled.

3. Oct 4, 2007

### cherryrocket

REVISION to simple velocity Q.

***REVISION***
Juanita left on a walk 45 min ago. She is traveling at 4.5 km/h. How fast must you travel to catch up to her in 1.0h"?

Juanita t=45 min +1.0h min v=4.5 km/h
d=vt = (4.5km/h)(1.75h) = 7.8 km

Me -
v=d/t = (7.8km/1.0h) = 7.8 km/h

I must travel at 7.8 km/h to catch up to her in 1 hour.

Is it this? For some reason the answer still doesn't seem right...

4. Oct 4, 2007

### learningphysics

You aren't rounding your answer properly. It should be 7.875km/h, which is 7.9km/h when rounded to 2 sig.figs.

5. Oct 4, 2007

### cherryrocket

So then I did get the right answer, just didn't round properly, right? Thanks!

6. Oct 4, 2007

### learningphysics

yeah. no prob. But why did you think your answer was wrong?

7. Oct 4, 2007

### cherryrocket

I don't know, I just thought it was too easy to be the right answer... does that make sense? lol

ps. how do you close a thread when a question is solved?

8. Oct 4, 2007

### learningphysics

Yeah, I understand that.

I'll mark the thread as "SOLVED". It won't close it, but that's ok.