- #1
kenway
- 13
- 1
I honestly don't know how to find the friction, much less frictional torque, when given things like this.
1. Homework Statement
"If you lift the front wheel of a poorly maintained bicycle off the ground and then start it spinning at 0.72rev/s, friction in the bearings causes the wheel to stop
in just 12s.
If the moment of inertia of the wheel about its axle is 0.30kg\m2 , what is the magnitude of the frictional torque?"
2. Homework Equations
I know:
Στ=Iα
α=Δω/Δt
I=mr2
Like I said, I have no idea how I am supposed to use the given variables to find friction.
This is an attempt I tried:
α=Δω/Δt
=0.72/12
=0.06m/s2
So I can now find torque with the angular acceleration:
∑τ=Iα
= (0.30kg/m2)(0.06m/s2)
= 0.018Nm
That's a small number that I'm pretty sure isn't right. Even if it is, I don't know where to go from here to find friction. If someone could just guide me/give me equations then I'd appreciate it
thanks!
1. Homework Statement
"If you lift the front wheel of a poorly maintained bicycle off the ground and then start it spinning at 0.72rev/s, friction in the bearings causes the wheel to stop
in just 12s.
If the moment of inertia of the wheel about its axle is 0.30kg\m2 , what is the magnitude of the frictional torque?"
2. Homework Equations
I know:
Στ=Iα
α=Δω/Δt
I=mr2
The Attempt at a Solution
Like I said, I have no idea how I am supposed to use the given variables to find friction.
This is an attempt I tried:
α=Δω/Δt
=0.72/12
=0.06m/s2
So I can now find torque with the angular acceleration:
∑τ=Iα
= (0.30kg/m2)(0.06m/s2)
= 0.018Nm
That's a small number that I'm pretty sure isn't right. Even if it is, I don't know where to go from here to find friction. If someone could just guide me/give me equations then I'd appreciate it
thanks!