[stuckstudent]

Hi all I'm just doing some practice papers and i've come unstuck on this question:





I can see why the N1 and N2 have a 1/2mg component, but I really don't get where the other parts come from. I've tried looking through my notes and Serway and Jewett but still can't figure it out. I've copy and pasted the answers underneath so people know what i'm on about

Cheers

[Stonebridge]

(Original post by stuckstudent)
Hi all I'm just doing some practice papers and i've come unstuck on this question:

I can see why the N1 and N2 have a 1/2mg component, but I really don't get where the other parts come from. I've tried looking through my notes and Serway and Jewett but still can't figure it out. I've copy and pasted the answers underneath so people know what i'm on about

Cheers

The terms come from taking moments as the question suggests.
The "fictional" force they are referring to is centrifugal force and will act outwards from the centre of mass and have a value Mv²/R
There are three moments about each pivot point (where the truck is in contact with the road); the centrifugal force moment and the reaction at the other pivot, as well as the weight.

The maximum speed is for the case where the reaction of the inner wheel is just equal to zero. The truck will then tip.