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a block of mass m slides down a frictionless incline. it is released at height h above the bottom of the loop. when it reaches the bottom, it begins going up a semi-circle of angle 45 degrees and radius R. the point where it begins going up the semi circle is labeled point A. basically, the block has acquired a certain velocity, and then starts going up a ramp. the point where the ramp begins is point A.

the question is, what is the force by the inclined track on the block at point A?

i realize the force by the track on the block is the normal force, however it appears this force would also be a function of the velocity, and not just of the mass of the block, but i am not sure. i am stuck because i am not sure if the force would simply be the normal force, or if it would be a function of the velocity (i know how to find the velocity).

am i totally wrong, and the force is simply the normal force, and not a function of the velocity? if there is acceleration upward at point A, which is what i suspect, then is it dependent on velocity (as i can only imagine it is)?

any help would be greatly appreciated.

this is problem 2-25 in thornton/marion's classical dynamics, part (a)