# Skating and friction

Poetria

## Homework Statement

Which of the following could help to increase average velocity of the left skate of the person:

Decreasing the static friction coefficient between the skate and the ground.

Increasing the static friction coefficient between the skate and the ground.

Decreasing the kinetic friction coefficient between the skate and the ground.

Increasing the kinetic friction coefficient between the skate and the ground.

Increasing the distance between the lines (circa 5m)

Decreasing the distance between the lines.

## The Attempt at a Solution

I think increasing the static friction and decreasing the kinetic friction would help. Static friction works in the direction of motion, does it?

Homework Helper
Gold Member
Increasing the distance between the lines
What lines? Have you left out some of the problem statement? I would have guessed the distance between the feet, but 5m stretches more than just the imagination.
Static friction works in the direction of motion, does it?
Friction, whether static or kinetic, opposes relative motion of the surfaces in contact. It will work in the direction of motion of the body (skater, walker, car, train...) if the part in contact with the ground is trying to go the other way.

• Poetria
Poetria
Oh it is my fault. It is a video, you know. I have drawn it.

Yes, I know that friction opposes motion but if you push ice with a skate to gain speed, isn't the static friction opposing pushing but favouring gliding?
The example of a dog running on ice was simpler. :)

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