Physics Class help?!?

Question

This is one of the problems's on my sister's Web assign and she wants to know how to go about figuring it out. (step by step or a simple run through of the procedure) and what the heck do they mean by the grade?

"A hill that has a 16.5% grade is one that rises 16.5 m vertically for every 100.0 m of distance in the horizontal direction. At what angle is such a hill inclined above the horizontal?"

Answer 1

The grade is defined - 16.5 m vertically for 100.0 m distance horizontally or 16.5% - It is a common word referring to the slope of a line.

To solve this problem draw a right triangle with the vertical piece being equal to 16.5 m and the horizontal piece being equal to 100 m, then solve for the tangent angle.

Tangent (x) = Opposite side length / Adjacent side length

Tangent (x) = 16.5/100

Tangent (x) = 0.165

x = tan^(-1) (0.165)

x  = 9.369385

The hill is inclined approximately 9.4 degrees above the horizontal.

Hope this helps...b.