Haven't done any physics problems in about two years now, so I could be wrong but!
Believe me, if I could do this stuff, I would. Thanks in advance to all who help answer, attempt to help, or nudge me in the right direction. Now, I don't want you guys to think that I want you to do my homework, I don't need the answers I just need a nudge in the right direction, like even the formula or something that I'm supposed to use would be good. Okay, so here they are:
1. A 64-kg person on skis is going down a hill sloped at 30° from the horizontal. The coefficient of friction between the skis and the snow is 0.12. What would be the magnitude of the acceleration?
F = ma, Ff = (coefficient)(normal force)
where F = sum of forces, Ff = force of friction
Remember that the normal force is perpendicular to the surface (that's where the 30 degrees comes in play)
Forces in play are: Gravitational force (mg), frictional force, and normal force
See if that helps.
2.
A. A 60-kg person on skis starts from rest down a hill sloped at 36° from the horizontal. The coefficient of friction between the skis and the snow is 0.20. After the skier had been moving for 5.0 s, the friction of the snow suddenly increased and made the net force on the skier zero. What is the new coefficient of friction?
B. How fast would the skier now be going after skiing for another 5.0 s?
Uhhh I honestly don't remember enough. I'll look at it in a few minutes.
3. A 240-N box is placed on an inclined plane that makes a 40.0° angle with the horizontal. Find the component of the weight force parallel to the plane's surface.
I'd have to draw this out to explain it. Sorry. But remember that that particular force is composed of two parts, the x-component and the y-component (where negative y is in the same direction as gravity and positive x is perpendicular and to the right of y). The rest is trigonometry and knowing the other forces.
Hopefully that last part made sense. I find it always helps to draw out concrete problems like these.
» Thu Dec 08, 2011 12:40 am 
