# Math Help - Physics and math

1. ## Physics and math

Hi guys. Iv got a real fun one for you today. Its actually a physics question but its solved using math equations (substitution or elimination)

A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7 m/s. The coefficient of kinetic friction between skis and snow is 0.11. Determine how far the skier will slide before coming to a rest.

We can consttruct a triangle with that and figure out FG parallel(Pa) and FG perpendicular(Pe). so

$\frac {sin90}{9.81m} = \frac {sin4.7}{FgPa}$
Im not sure what to construct my other equation from. Id appreciate help. Thanks guys

2. Originally Posted by ffezz
Hi guys. Iv got a real fun one for you today. Its actually a physics question but its solved using math equations (substitution or elimination)

A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7 m/s. The coefficient of kinetic friction between skis and snow is 0.11. Determine how far the skier will slide before coming to a rest.

We can consttruct a triangle with that and figure out FG parallel(Pa) and FG perpendicular(Pe). so

$\frac {sin90}{9.81m} = \frac {sin4.7}{FgPa}$
Im not sure what to construct my other equation from. Id appreciate help. Thanks guys
I would use the work-energy theorem.

$W_{nc} = \Delta E = \Delta PE + \Delta KE$

The only nonconservative force here is the frictional force, so
$-f_k x = (mgh - mgh_0) + \left ( \frac{1}{2}mv^2 - \frac{1}{2}mv_0^2 \right )$

So define a zero point for your gravitational potential energy and find your normal force. The skier stops when v = 0 m/s. (You will also need to find your h's in terms of the slope length x and the angle the slope makes with the horizontal.)

-Dan