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For most material pairs, how does the static friction coefficient compare to the kinetic one?

Static is usually larger, so it takes more force to start sliding than to keep sliding.

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  1. Static is usually larger ✔
  2. Kinetic is usually larger
  3. They are always equal

Why: That is why a heavy box is hardest to push right before it budges, then gets easier. For dry steel on steel, static is about 0.6 and kinetic about 0.3.

Huh, didn't know that: Friction coefficients have no units; they are a ratio of two forces.

The dad joke
Static friction is like me on a Monday morning. Hard to get started, easier once I'm moving.
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References

Answer: Static is usually larger. That is why a heavy box is hardest to push right before it budges, then gets easier. For dry steel on steel, static is about 0.6 and kinetic about 0.3.

  1. OpenStax University Physics Volume 1: 6.2 Friction openstax.org/books/university-physics-volume-1/pages/6-2-friction
    the static friction is usually greater than the kinetic friction between two objects
    Checked 2026-10-10.
  2. OpenStax University Physics Volume 1: 6.2 Friction openstax.org/books/university-physics-volume-1/pages/6-2-friction
    Coefficient of friction is a unitless quantity with a magnitude usually between 0 and 1.0.
    Checked 2026-10-10.

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