| For some reason I cannot reply to your comment wizzwizz4. We are talking about dynamic friction in it's simplest form. You can treat it as simple math problem too. Let's consider two extreme cases: A: Side slip is 1m/s and wheel spin zero or very small. B: Side slip is 1m/s and wheel spin extremely big, let's say 1000m/s. I think we can agree that friction is always opposite to surface speed. If wheel spin is on x axis and side slip on y: On A case friction is (0, 1).normalized() * friction-coefficiency => (0, friction-coefficiency) On B case friction is (1000, 1).normalized() * friction-coefficiency => [approximately] (friction-coefficiency, 0) On classroom teacher says that slip does not matter. What teacher actually means that slip does not effect into -magnitude- of friction but this is left behind because problem is presented in context of 1D. Tho in 1D slip still matters little bit because there is difference is slip 1m/s or -1m/s. |
This isn't intuitively obvious to me. One explanation says "must be true", another explanation says "might be false". I'd want to run an experiment with a toy car on a polished surface. Unfortunately, I'm quite a way from the nearest place I could set up such an experiment.