Undergrad Conservation of angular momentum -- spinning a bicycle wheel in space

Click For Summary
In a frictionless environment, a bicycle wheel in space will not stop rotating unless acted upon by an external force. The conservation of angular momentum remains intact as the wheel's friction with the axle causes both to eventually rotate at the same rate, rather than stopping completely. If the wheel is mounted on a non-rotating bike, the torque will cause the bike to rotate, conserving the total angular momentum of the system. Thus, the initial assertion that angular momentum is violated is incorrect. The system continues to exhibit conservation principles as long as no external forces intervene.
abdossamad2003
Messages
68
Reaction score
4
Suppose we have a rotating body like a bicycle wheel in space away from gravity. This body stops after a while due to friction between the wheel and wheel axles. Is not the conservation of angular momentum violated?
 
Physics news on Phys.org
If it's just the wheel, then there's no axle exerting friction and the wheel will rotate without slowing forever. If it is mounted on a non-rotating bike, then the bike will take up the torque and begin rotating, conserving angular momentum.
 
Reply
  • Like
Likes nasu and PeroK
abdossamad2003 said:
Suppose we have a rotating body like a bicycle wheel in space away from gravity. This body stops after a while due to friction between the wheel and wheel axles. Is not the conservation of angular momentum violated?
You are wrong to say that the body stops. As per @Halc's answer, the wheel slows and the axle spins up until both are rotating at the same rate. Then the wheel and axle continue to spin eternally, at rest with respect to each other.
 

Thread 'Mousetrap Car Energy efficiency'

For simple comparison, I think the same thought process can be followed as a block slides down a hill, - for block down hill, simple starting PE of mgh to final max KE 0.5mv^2 - comparing PE1 to max KE2 would result in finding the work friction did through the process. efficiency is just 100*KE2/PE1. If a mousetrap car travels along a flat surface, a starting PE of 0.5 k th^2 can be measured and maximum velocity of the car can also be measured. If energy efficiency is defined by...
View full post »

Similar threads

Spinning Bike Wheel Example, how is angular momentum conserved?
  • · Replies 9 ·
Replies
9
Views
5K
Conceptual questions about Angular Momentum Conservation and torque
  • · Replies 2 ·
Replies
2
Views
3K
Conservation of Angular Momentum and a Spinning Bicycle Wheel
  • · Replies 5 ·
Replies
5
Views
4K
High School The physics of flywheel launchers (like tennis ball shooters)
  • · Replies 60 ·
3
Replies
60
Views
5K
Conservation of Angular Mometum for a Car/Earth System
  • · Replies 20 ·
Replies
20
Views
2K
Undergrad Conservation of angular momentum in the iceskater example
  • · Replies 10 ·
Replies
10
Views
605
ABS system on a two-wheeled vehicle - Conservation of Angular Momentun
  • · Replies 7 ·
Replies
7
Views
1K
How Does Angular Momentum Apply to Earth and Spinning Bike Wheels?
  • · Replies 36 ·
2
Replies
36
Views
4K
Undergrad Conservation of angular momentum during collisions
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad Changing the RPM of a frictionless spinning wheel in a box
  • · Replies 4 ·
Replies
4
Views
1K