# Wheres the reaction in an ice skater who thrust sidewards with parallel skates

## Main Question or Discussion Point

when you walk the reaction of your thrust is the earth going very slightly in the other sense

but how can an ice skater that having the skates perfectly parallel while thrusting pushes sidewards and advances forward besides taking into account that being the skates parallel the longitudinal force tends to 0

so is the ice skating keeping the skates parallel to thrust a case where the reaction is sidewards instead of backwards or what?

how is the earth pushed backwards by the ice skater while keeping the skates parallel and thrusting sidewards to go forward?

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russ_watters
Mentor
A skater cannot be pushed forward by parallel skates. They must be angled somewhat away from each other.

russ_watters said:
A skater cannot be pushed forward by parallel skates. They must be angled somewhat away from each other.
PMSL! Noooo no no no. All the skater needs to do in order to push forwards (with parallel skates) is to lean forwards (putting his weight forwards) whilst tipping his skates forward also. The same concept goes with roller blades as I am a roller blader. :uhh:

You can even accomplish forwards thrust with skateboards (as they have parallel wheels) no? I do this all the time and I don't even need to use my foot to push forwards. I can start off by just pushing my weight forwards whilst totally on the skateboard. Momentum and weight transfer does the rest. Can even do this with snowboards (on flat ground) by just using forwards weight transfer (although its harder because there are no wheels -- but 'tis possible).

If you want to gain speed though by turning and changing direction, you have to angle the blades later on whilst using thy knees to use weight transferring for momentum. :rofl:

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LeonhardEuler
Gold Member
PhysicsEnthusiast said:
PMSL! Noooo no no no. All the skater needs to do in order to push forwards (with parallel skates) is to lean forwards (putting his weight forwards) whilst tipping his skates forward also. The same concept goes with roller blades as I am a roller blader. :uhh:

If you want to gain speed though, you have to angle the blades later on whilst using thy knees to use weight transferring for momentum. :rofl:

You can even accomplish forwards thrust with skateboards (as they have parallel wheels) no? I do this all the time and I don't even need to use my foot to push forwards. I can start off but just pushing my weight forwards whilst totally on the skateboard. Momentum and weight transfer does the rest. Can even do this with snowboards (on flat ground) by just using forwards weight transfer (although its harder because there are no wheels -- but 'tis possible).
This is not true. The skater can not begin moving simply by leaning foward. The only thing this will accomplish is moving the normal force farther and farther up on the skates until it can't go any farther and the skater begins to rotate. The skater must either push sideways or very slowly try to begin walking slowly enough that the force of static friction between the blade and the ice will be sufficient to push him foward.
I've seen skateboarders move themselves foward without kicking. They always tack back and forth diagonaly.

LeonhardEuler said:
This is not true. The skater can not begin moving simply by leaning foward. The only thing this will accomplish is moving the normal force farther and farther up on the skates until it can't go any farther and the skater begins to rotate.
Errr no. The skater can begin slowly moving (although limitedly) by simply leaning forwards with the help of his arms outwards infront of his torso (shifting his weight forward). One also needs to use his knees to spring forwards in order to generate forwards momentum.

He would however need to gain much more speed by using his back foot to push forwards. Another term for this is forward sculling or forward (straight-line or fixed-angle) stroking. It is a basic skill taught at the beginner's level. There are also different kinds of forwards stroking also. :yuck:

For race competitions though, like in speed skating, they need to run with their skates from the startline and then glide afterwards with fixed angle stroking to maintain their speeds (for a limited time of course). :tongue2:

http://home1.gte.net/pjbemail/ForwardStroke.html

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this link clearly states that after the start the skates are kept parallel at all times and it coincides with my experience , you can thrust with parallesl skates

http://www.bcso.bc.ca/resources/Athlete%20Resources/Speed%20Skating%20Drill%20Book.pdf [Broken]

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