Fault the wrong friction formulae

Exercise and reference answers

Questions

1. Question

   Three of these expressions for the least coefficient of friction are wrong.

   Choices

   1. Item

      mu = v^2 / (rg)

      Correct

      Yes

   2. Explanation

      leaving out g makes this an acceleration, not a ratio

      Item

      mu = v^2 / r

   3. Explanation

      this inverts the expression entirely

      Item

      mu = gr / v^2

   4. Explanation

      the speed must be squared

      Item

      mu = v / (rg)

Instructions

Three of these formulae for the least coefficient of friction are wrong. Fault each.