PHYS 101 | Statics 4 - Wheelchair Over a Curb

Yet another problem about pushing a wheelchair over a curb. This one involves a limit where the normal force goes to zero, so it "on the edge" of static.
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[@channies.dimples]

Thank you so much professor

[@eileenparkes3060]

The Wheelchair ,being pushed very fast , mounting kerb at high speed ...hence the Impact huge! serious!
Unconsciousness 2 hrs. Still very ill but improving 8 years on

[@eyesofakz]

What an explanation man !! Really appreciate that

[@itachu.]

thanks sir this really brushed my fundamentals at a very good level

[@Prof-Hafner]

Glad to hear that

[@jamiefoy4531]

Great teacher!

[@imalshapathirana4899]

Great explanation👍

[@prashanthn625]

Excellent Explanation. I have a doubt...
So when h=0, the force required will be zero, but is it not the case that there should be minimum force required for the wheel to keep rolling on a flat surface?

[@itachu.]

in such case too , you have to calculate force to get the body in pure rolling that is the point of contact remains at rest... mathematically you can know whether friction acts or not , however to be on safer side you always consider it the STATIC friction

[@prashanthn625]

@@itachu. So can we write,
Total Force= Force required for Rolling + Force required to overcome the curb (if any)

[@itachu.]

@@prashanthn625 yes incase you are calculating for a motion which is initially in translational and after some time, it passes through a curb with an another external force
you can form the equations as
1) translational motion equation to get acceleration or whatever term that's missing
2) balance the torque about point of contact or if you already know what the acceleration is , you can calculate the torque about the centre of mass that is rotating about the point of contact
3) as the point of contact remains at rest , a = R*(angular accn)
just make sure the question/situation mentions rolls without slipping that implies , the point of contact does not slip hence at rest at that instant of the moment