Friction

Question 1

What is the model F is less than = to mew R means?

Answer 1

Say particle on floor, no tendency to slide = no friction

Say you raise floor on slope. If the floor is rough, there is a tendency to slide, but if angle is small, it is likely that the Friction is enough to counter the weight in that plane. In this case, friction is LESS THAN MEW R

but once you reach the POINT OF SLIDING, the friction perfectly balances the weight . In this case the friction = MEW R and the partial about to slide the friction is LIMITING

MEWR is the max friction, past this it won’t increase, thus if you raise slope, now weight bugger than friction, it will fall

Question 2

Remember for range questions what to do about inequality?

Answer 2

We’ll have to remmeber it’s equal at that and more, so make sure itsless than equal or more than equal to

Question 3

Another way to think about limiting equilibrium etc

Answer 3

So you push a heavy object, but because force not string enough it’s not about to move. As a result the friction = your push, and it’s not max friction so it’s LESS THAN EQUAL TO MEWR.

However once at point of movement, this is max frictions and F = Mew R. At this point it still able to counter all forward push so doesn’t move

However now friction is maxed out and so extra push will cause it to accelerate .

Question 4

Remember for resolving friction, need reaction force, what to do for that

Answer 4

For reavtion force resolve vertically first, don’t forget reaction will be slightly different