Friction that allows us to walk depends on gravity to convert our mass to weight which holds our feet against the surface where static friction enables the soles of our shoes to push off against the surface of the Earth.Okay there puppy. Explain how a rocket works in space. What friction do they use to move?
And I'll even ignore the whole first law thing.
Even when ice skating, kinetic friction keeps the blades sliding against the ice in a forward direction, and static friction allows the skates to push off to propel the skater forward.
Even a rocket engine, which otherwise could be used to propel you in a frictionless environment, depends on the difference in force between friction caused by great pressure of propellant exhaust on a small area (exit pressure) and the lesser friction of propellant exhaust flowing through a larger area (free stream pressure). The equation for rocket thrust shows this:
rocket thrust=mass flow rate×exit velocity+(exit pressure−free stream pressure)×exit arearocket thrust=mass flow rate×exit velocity+(exit pressure−free stream pressure)×exit area
The coefficient of friction is a measure of how strongly two surfaces will stick together. It's the ratio between the force necessary to induce sliding, and the pressure holding the two surfaces together. It can be used to calculate the amount of friction:
F=u×NF=u×N
FF is the frictional force
uu is the coefficient of friction
NN is the normal force (perpendicular to both surfaces, which presses them together)
If surfaces could slide with no force at all, the numerator of their coefficient of friction would be zero, the coefficient itself would be zero, and the frictional force between those two surfaces would be zero. The maximum coefficient of friction is one, and the minimum is zero.
Friction exists everywhere in the Universe. To have no friction, there would have to be no gravity, no electromagnetic force, no gluons to hold atomic nuclei together, and no bosons to allow the buildup of heavy nuclei in stars. All would be chaos. Newton's third law would be inoperative. The universe would be a soup of uniform density with no structure. Entropy would tend to be maximal. You would not be able to walk.