# Physics Problem involving Kinematics

1. Sep 20, 2007

### bbface_assassin

1) A typical car's brakes can create a maximum acceleration of less than 5 m/s2 . How
close can you get to a stop sign before you start braking?

I don't think it's even doable, since there's no initial velocity. Or am I wrong?

2. Sep 20, 2007

### olgranpappy

you are correct, sir. though, you could write the answer in terms of the unknown v_0.

3. Sep 20, 2007

### bbface_assassin

Oh. So then my answer would be in variables, and not actual numbers?

4. Sep 20, 2007

### olgranpappy

yep. you can write the answer for the shortest braking distance in terms of the initial velocity and the acceleration... you might be able to guess it (up to a factor of 1/2) from dimensional analysis (i.e., looking at the units).

5. Sep 20, 2007

### bbface_assassin

So can I use V^2 = Vo^2 + 2ax as the formula for solving this?

6. Sep 20, 2007

### olgranpappy

yeah, since you know what v has to be when the car has stopped. you can solve for x in terms of v0 and a.