Search found 95 matches
- 15 Oct 2023, 4:12pm
- Forum: Touring & Expedition
- Topic: Across Spain by rail
- Replies: 15
- Views: 5164
- 27 Sep 2023, 6:31am
- Forum: Touring & Expedition
- Topic: Tour of the Ardèche and Vercors on the tandem
- Replies: 16
- Views: 3996
- 16 Jul 2023, 3:30pm
- Forum: Does anyone know … ?
- Topic: Bike on train, this week.
- Replies: 10
- Views: 944
Re: Bike on train, this week.
I think Thursday is a full on strike so very, if any, trains.
- 4 Apr 2023, 8:36am
- Forum: Family Cycling
- Topic: Irwell Sculpture Trail
- Replies: 9
- Views: 4752
- 4 Apr 2023, 8:20am
- Forum: Family Cycling
- Topic: Irwell Sculpture Trail
- Replies: 9
- Views: 4752
Re: Irwell Sculpture Trail
Carry on Woodhill Rd and park at Burrs country park, last section of the road is cobbled, it is Bury after all.
- 4 Apr 2023, 8:04am
- Forum: Family Cycling
- Topic: Irwell Sculpture Trail
- Replies: 9
- Views: 4752
Re: Irwell Sculpture Trail
Plenty of free parking there and another caff!
- 4 Apr 2023, 7:43am
- Forum: Family Cycling
- Topic: Irwell Sculpture Trail
- Replies: 9
- Views: 4752
Re: Irwell Sculpture Trail
From Woodhill Rd which leads to Burrs (staying on the site?) up to Greenmount is an old rlwy so traffic free, just under 4 miles with caff/ice cream at the top end - The Hub.
- 4 Apr 2023, 5:57am
- Forum: Family Cycling
- Topic: Irwell Sculpture Trail
- Replies: 9
- Views: 4752
Re: Irwell Sculpture Trail
It isn't. Footpath status, narrow and very muddy in places. Sustrans 6 gives a decent ride north from Bury to Rammy.
- 23 Sep 2022, 6:23pm
- Forum: Helmets & helmet discussion
- Topic: Crash and helmet
- Replies: 329
- Views: 22895
Re: Crash and helmet
For us ultimately the system is the Earth if we assume no interaction with anything o/s our planet.Jdsk wrote: ↑23 Sep 2022, 6:09pmIf that's a closed system then momentum is conserved.
Billiard balls on a table are not a closed system because of their interactions with the surface, cushions, air etc, as above. So the momentum of the balls alone does not need to be conserved. The momentum of the whole system does.
Jonathan
- 23 Sep 2022, 6:01pm
- Forum: Helmets & helmet discussion
- Topic: Crash and helmet
- Replies: 329
- Views: 22895
Re: Crash and helmet
The system is the reference frame which includes all the forces and their interactionsJdsk wrote: ↑23 Sep 2022, 5:33pmPlease could you each describe the limits of the system that you are considering.dmrcycle wrote: ↑23 Sep 2022, 5:17pmNo absolutely not the case, thats conservation of energy. Momentum is only conserved if there are no other forces acting. Newton stated that is the case.
See
http://teacher.pas.rochester.edu/PHY_LA ... _Laws.html
Quote
Friction between moving bodies and their surroundings means there is an external force acting on them, so that conservation of momentum is not applicable.
Confusion between conservation of momentum and conservation of energy is what is the issue here. I can appreciate it might have been some time from school level physics but the information can be looked up. In a collision energy is conserved momentum is not unless its a perfect situation (similar to two billiard balls). If there is friction, deformation, heat, sound etc then conservation of momentum does not apply. The momentum (mass x velocity) is not the same after the interaction. Think about it, otherwise we would all be bumping around never stopping transferring 100% of our momentum between things we touch. Nothing slowing down. When energy is absorbed and converted from kinetic energy to heat (aka braking) it cant be conserved as you slow down and have less momentum. This is basic school level stuff.
Thanks
Jonathan
- 23 Sep 2022, 4:19pm
- Forum: Helmets & helmet discussion
- Topic: Crash and helmet
- Replies: 329
- Views: 22895
Re: Crash and helmet
Momentum is one of the fundamental conserved quantities no matter what energy conversions are taking place.
- 22 Sep 2022, 2:55pm
- Forum: Helmets & helmet discussion
- Topic: Crash and helmet
- Replies: 329
- Views: 22895
Re: Crash and helmet
Oh dear, how wrong can one be.
- 28 Mar 2022, 9:06pm
- Forum: The Tea Shop
- Topic: Cycle mag inserts - is this a record?
- Replies: 14
- Views: 642
Re: Cycle mag inserts - is this a record?
I had none.
- 31 Oct 2021, 6:35pm
- Forum: Does anyone know … ?
- Topic: overburys touring bikes
- Replies: 41
- Views: 7260
Re: overburys touring bikes
I was a regular customer in the early 70s when Arthur Powell ran the shop. It was THE shop for CTC members.
- 2 Oct 2021, 8:40am
- Forum: The Tea Shop
- Topic: HMS Vigil - any fans out there?
- Replies: 104
- Views: 3453
Re: HMS Vigil - any fans out there?
In the simplest model of flotation a ship floats because the upward buoyant force is greater than the weight of the ship.
The buoyant force must equal the weight of the ship.
The buoyant force must equal the weight of the ship.