# Two cars, acceleration, and speed.

1. Aug 23, 2007

### chaotixmonjuish

At the instant a traffic light turns green, a car starts moving with a constant acceleration a of 3.07 m/s2. At the same instant a truck, traveling with a constant speed of 9.72 m/s, overtakes and passes the car. How far beyond the traffic light will the car overtake the truck?

I've been working on this question for a while. I tried integrating the 3.07, but then I just screwed it up somewhere. I just need help trying to discern what to do. I've taken calculus, however, I have never been taught how to apply what I have learned.

2. Aug 23, 2007

### G01

I don't think you'll need to much calculus in this problem. You may be making this harder than it has to be.

Using the three standard kinematic equations which are derived in all intro physics texts, can you give me equations for the positions of the car and truck at any time, t? If you can, it is just a matter of setting the two equal to each other and solving for time.

3. Aug 23, 2007

### chaotixmonjuish

I actually posted everything the question gave me. I'm very new to physics. In fact, all I have taken is Calculus with Theory.

4. Aug 23, 2007

### learningphysics

Can you give an equation for displacement in terms of time for a vehicle undergoing constant acceleration?

Can you give an equation for displacement in terms of time for a vehicle with constant velocity?

5. Aug 23, 2007

### chaotixmonjuish

No, I'm really not sure how to attempt this problem. I just lifted what i put there off the webpage where hte question is.

6. Aug 23, 2007

### learningphysics

There are kinematics equations that you need to know and understand... such:

$$s = \frac{v1 + v2}{2}*t$$

and

$$s = v1* t + \frac{1}{2}at^2$$

If you don't recognize these equations then you should really study them in your text before attempting this problem.

7. Aug 23, 2007

### learningphysics

Is this something you're studying on your own or are you taking a physics class?

8. Aug 24, 2007

### G01

I agree. If your doing problems like this, you are going to have to be familiar with these equations, plus a couple others like them. If you do not recognize these equations, you should probably reread the chapter that you are on(If you are studying on your own and don't have a book, I suggest getting one if possible), paying special attention to the equations of motion that are derived. They are the key to problems of this nature.