Calculating push force up a ramp using rolling friction instead of drag friction

[DonnaLee]

How do I calculate the required push force (in kgf) for pushing a wheelchair up a ramp?

- the ramp has a 5 degree incline
- the weight of the chair and person in it totals 96.8 kg
- the wheelchair has 4 wheels, all of equal diameter (15 cm)
- the wheels on the wheelchair have a rolling coefficient of friction with the floor of 0.1

I have to use rolling friction and thats the part thats tripping me up.
I am really stuck on this. Any help would be greatly appreciated thank you

 

[Deleted member 4993]

How do I calculate the required push force (in kgf) for pushing a wheelchair up a ramp?

- the ramp has a 5 degree incline
- the weight of the chair and person in it totals 96.8 kg
- the wheelchair has 4 wheels, all of equal diameter (15 cm)
- the wheels on the wheelchair have a rolling coefficient of friction with the floor of 0.1

I have to use rolling friction and thats the part thats tripping me up.
I am really stuck on this. Any help would be greatly appreciated thank you

Did you calculate the normal force(N) that will be applied on each wheel?

 

[DonnaLee]

each individual wheel had normal force of 237.4 N applied to it because all 4 wheels are the same size.

I tried this formula to calculate force required to overcome rolling resistance: Fr = cl W / r, where cl= coefficient of rolling friction, W=mag and r= radius of wheel.

came up with 0.081 kgf per wheel x 4= 0.324 kgf total for the wheelchair (rolling CoF of 0.1)

 

[Deleted member 4993]

Did you draw a FBD of the wheel chair as a particle on slope?

You are forgetting to account for the slope. Write the equilibrium equations and solve.

This is a bit tricky problem - be careful!