How Fast is the Car Going Based on Passenger Force Components?

[hayowazzup]

[SOLVED] Need help with finding the speed

Homework Statement

A car goes around a curved stretch of flat roadway of radius R = 94.0 m. The magnitudes of the horizontal and vertical components of force the car exerts on a securely seated passenger are, respectively, X = 215.0 N and Y = 510.0 N.

At what speed is the car travelling?

i have no idea how to solve this.

Homework Equations

not quite sure

The Attempt at a Solution

:(

 

[hayowazzup]

a= v^2 / r
v = SQRT(ar)
Y=F =510N= mg , m= 510/9.8=52.04
X=F= 215N=ma , a= 215/52.04=4.13
v= SQRT(4.13*94)

 

[tiny-tim]

a= v^2 / r
v = SQRT(ar)
Y=F =510N= mg , m= 510/9.8=52.04
X=F= 215N=ma , a= 215/52.04=4.13
v= SQRT(4.13*94)

Hi hayowazzup!

Yes that looks good …

though I'd have shortened it by writing v = √(rg 215/510) …

then you can do all the calculation in one go.

 

[hayowazzup]

umm i got 19.13m/s
Convert it now km/h, 19.13 * (1000/(60*60))= 5.315km/h
but the answer in the book is 68.9km/h

 

[alphysicist]

hayowazzup,

I believe your conversion factor is upside down; you divide by 1000 to convert from meters to km, and you multiply by 3600 to convert from (1/s) to (1/hours).