- #1
The Head
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- 2
Homework Statement
A long board is free to slide on a sheet of frictionless ice. A skater skates to the board (laid horizontally relative to the skater's motion) and hops onto one end, causing the board to slide an rotate. In this situation, are angular and linear momentum conserved?
Homework Equations
sum of torques = I* alpha
sum of forces = ma
The Attempt at a Solution
I understand that the reason that the angular momentum and linear momentum are conserved is because there are no outside forces or torques, so mathematically it makes sense. I'm struggling with this conceptually though.
So when this board begins to slide and rotate, are we saying the angular momentum is zero? Because if the board were to rotate, so would the person attached to it. I can see that the board will eventually straighten out, but and then just stay straight, but I'm caught up on the part where it's sliding.
Also, I imagine there is friction of some sort to keep the skater on the board (and get the board moving). But in order for the board to slide, wouldn't the board also have to slide against the skater's shoes in order to straighten out? Otherwise, it seems as if the board would just stay horizontal relative to the skater's line of motion. And if there's friction, there would be some loss of energy. I'm less concerned about this at the moment, and more so about the bit in the second paragraph, but it's just not clicking for me fully and I'd like to completely understand.