Momentum. Gravity. How do they relate with respect to skiers doing fancy tricks as they speed downhill? Have you been watching the Olpians?

Doesn't gravity also slow them down tom? Thank you for your reply. I was kinda hoping you'd show up. Thanks! :)

No.

The force of gravity is represented by a vector (a quantity that has both a numerical value and a direction)---that is, it can be represented by two forces (components), at a 90 degree angle, that allow us to analyze how gravity affects the skier.

The component of the gravitational force is opposed by the force of friction against the snow and the force of air friction that the skier encounters against the air as he goes down the slope. (That’s why the position of the skier as he skies is to encounter the least resistance to his forward process.)

And doing the fancy tricks will probably change the air resistance for that brief length of time as well 

Hope that helps---if not, let me know.

Thank you for leaving the door open m'dear because I do have another question.  Take the universe. Do other celestial bodies have gravitational impact on one another? As a planet goes by does it slow down, speed up, remain unaffected by its proximity to the gravitational pull of what it is passing by? I hope the question makes sense because I don't know how else to ask it tom! :)

Let me try this: (And let's stick with Newton rather than Einstein to make it easy conceptually.) 

Gravitational interactions do not simply exist between the earth and other objects; and not simply between the sun and other planets. Gravitational interactions exist between all objects with an intensity that is directly proportional to the product of their masses (and inversely proportional to the square of the distance between them.) Gravity is universal. Of course, most gravitational forces are so minimal to be noticed. Gravitational forces are only recognizable as the masses of objects become large (and closer together).

So yes, they affect one another, but frequently are too small to be measured.

Thank you for your thoughtful and helpful reply tom. Did you see my question on "gravity assist"? The assist can be to speed up, slow down or change the direction of an object.  So that seems rather amazing to me. :)

No, not yet.  (If this doesn't help, comment on this and post the link to your gravity assist question.)

You obviously know skiers ski "down" a hill.  If there were another hill at the bottom identical to the one they just skied down.  And now they had to ski "up."  They wouldn't be able to do it. 

The force of gravity is still acting on the skier, but now the amount of energy he had at the start of his run has been expended in skiing quickly down the mountain  (The potential energy given to him by gravity because of his height at the top of the ski run has been converted to kinetic energy as he went down the mountain and used up when he stops at the bottom.)  Now he would need to be able to find another source of energy to ski up again.  

(A small jet pack would work I imagine.)