# Homework Help: Physics distance and acceleration Problems

1. Oct 17, 2014

### Dhooy7

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

What acceleration does Marcus feel and how long does Marcus travel with the details: Marcos and Melissa are driving. Marcus's car travels 21 m/s and Melissa's travels 25 m/s. Marcus's car is 200 m behind Melissa's car when he hits the gas, giving constant acceleration. Marcus overtakes 12 sec?

2. Relevant equations

3. The attempt at a solution

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• ###### physics distance.jpg
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Last edited by a moderator: Oct 17, 2014
2. Oct 17, 2014

### Staff: Mentor

Welcome to the PF.

Those images are really hard to see. Can you please type your solution into the forum, so it is easier for us to help you? Thanks.

3. Oct 17, 2014

### Staff: Mentor

It is far preferable that you type details of your method and working, so respondants can read it easily and quote parts of it in their reply.

Presumably you post here hoping for assistance? So .... by making that effort you'll make it easy for people to help you.

I see you are new here so , http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

Last edited by a moderator: May 7, 2017
4. Oct 17, 2014

### Dhooy7

I got delta x=285.12 m
a=0.46

I did it another way with someone else and he said a=3.44 m/s and x=500m. Not sure which is right.

5. Oct 17, 2014

### Dhooy7

Mellia=Marcu's distance +200m.

I used vf2=vo2+2a (200m) and solved for a.
vf=25
vo=21
t=12

Then used delta x =vot+1/2at2

6. Oct 17, 2014

### Staff: Mentor

Check this. Whose car will travel the greatest distance after we start observing them?

Your equation seems to be solving for Marcu's car to attain 25 m/s when it reaches Mellia's starting point (being 200m from where he started).
EDITED

Last edited: Oct 17, 2014
7. Oct 18, 2014

### Dhooy7

So what is the right answer?

8. Oct 18, 2014

### Staff: Mentor

Your working is not correct. Try drawing a clear diagram that fits the scenario you are examining.

9. Oct 18, 2014

### Dhooy7

So neither of these are correct:

a=3.44 m/s and x=500m.

I got delta x=285.12 m
a=0.46

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