Re: University Physics

[Bob LaMontagne <rlamont@POSTOFFICE.PROVIDENCE.EDU>]

Tina

I would suggest the following:

use vf^2 = vi^2 + 2a(xf-xi)

The trick appears to be to let xi = vi*0.5sec.

Since vf=0,

0^2 = vi^2 - 2*6*(50 - vi*0.5)

giving vi = 21.68

Hope that's one of the answers! It would be embarrasing to post a wrong
solution to this group!!!!

Bob at PC

Tina Fanetti wrote:

> Does anyone here use University Physics by Reese?
>
> I am stuck on this problem, its multiple choice and I can get 3 of th=
> e 5 choices :(
>
> Here's the problem if anyone is interested....
> Assume that the brakes of your car can slow it with an acceleration o=
> f magnitude 6 m/s2.  If Homer steps onto the road 50 m in front of yo=
> ur car, what is the maximum speed you could be going in order to avoi=
> d hitting Homer?  Assume that it takes you 0.5 s to hit the brakes an=
> d that you have constant acceleration during braking. =20
>
> Tina
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429