# Motion at constant velocity

1. Sep 1, 2015

### Manh

You and your friend are in building four equal-length blocks apart, and you meet for lunch. Friend is 1.2 m/s and you are 1.6 m/s. The restaurant is between the two building and you and your friend will arrive at the same instant if both of you leave the buildings at the same instant. In blocks, how far from your building is the restaurant?

Can anyone guide me how to solve this problem? Thanks!

2. Sep 1, 2015

### SammyS

Staff Emeritus
Let's say that you travel a distance, x. What distance does your friend travel?

3. Sep 1, 2015

### Manh

The problem only provide me blocks but it does not provide me distance x? Therefore, it's the problem!

4. Sep 1, 2015

### SammyS

Staff Emeritus
Distance for this problem is in units of blocks.

I repeat: Let's say that you travel a distance, x. What distance does your friend travel?

5. Sep 1, 2015

### Manh

I think my friend travel in 4x? Can you give me second hint?

6. Sep 1, 2015

### SammyS

Staff Emeritus
No way is it 4x. Can't give much bigger hint than I gave.

Total distance traveled by the two of you is 4 (blocks).

You travel x (blocks). How far does your friend travel?

7. Sep 1, 2015

### Manh

Oh, is it 4 - x?

8. Sep 1, 2015

### SammyS

Staff Emeritus
Yes it is.

If each of you walks for a time, t, what distance does each of you walk?

9. Sep 1, 2015

### Manh

So, my friend walk 4 - x and I walk x.

10. Sep 1, 2015

### SammyS

Staff Emeritus

The problem gives a walking speed for each of you. Based on those speeds:
If each of you walks for a time, t, what distance does each of you walk?​

11. Sep 1, 2015

### Manh

Do I need the formula v=x/t to find our distances?

12. Sep 1, 2015

### SammyS

Staff Emeritus
Solve that for distance.

13. Sep 1, 2015

### Manh

The formula of distance is x = v * t. What do I plug in for t when it is not given?

14. Sep 1, 2015

### SammyS

Staff Emeritus
but v is given numerically.

just use the variable t.

Do you have much experience with algebra ?

15. Sep 1, 2015

### Manh

Oh, I see what I need to do this part now! I will have my answers in a moment.

16. Sep 1, 2015

### Manh

I got t=10/7. Is it correct? If so, should I express it in a decimal number?

17. Sep 1, 2015

### SammyS

Staff Emeritus
It may be the correct answer for something.

There should be two answers, one for you, one for your friend.

If you travel at 1.6 m/s, what distance do you travel in a time of t (seconds) ?

If your friend travels at 1.2 m/s, what distance does your friend travel in a time of t (seconds) ?

18. Sep 1, 2015

### Manh

These are my equations:
- My distance: x = 1.6*t
- My friend's distance 4 - x = 1.2*t
4 - 1.6t = 1.2t

From there, I solve for t to plug it back into my distance's equation. Am I correct?