- #1

michaelwiggin

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## Homework Statement

"A 60kg boy rides down an icy hill of 19º slope while standing on a 2.6kg flat-bottomed bathroom scale. Assume there is no frictional force between the bottom of the scale and the hill. The static friction force the scale exerts on the boy is ____.

## Homework Equations

... F = ma

F

_{f}=[tex]\mu[/tex]F

_{n}

Not sure what else... really its the theory of it that's getting me.

## The Attempt at a Solution

Well, my understanding is that if there was no friction between the boy and the top of the scale, then

*while*the scale was sliding down the hill, the boy would be sliding downward not only with respect to the hill (as a result of the acceleration of the scale) but also with respect to the scale. But because it asks for the

*static*friction of the scale on the boy, this must mean he's not moving, and thus when determining the friction we can use the usual F

_{f}=mgsin[tex]\theta[/tex] equation.

Thus 60kg(9.8m/s

^{2})(sin19) = 191.4

Any mistakes that you all notice?

Thanks!

-Michael