Search found 95 matches

by buryman
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.
by buryman
4 Apr 2023, 8:36am
Forum: Family Cycling
Topic: Irwell Sculpture Trail
Replies: 9
Views: 4752

Re: Irwell Sculpture Trail

https://youtu.be/Kbr6famKEUc

This may trundle past you.
by buryman
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.
by buryman
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!
by buryman
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.
by buryman
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.
by buryman
23 Sep 2022, 6:23pm
Forum: Helmets & helmet discussion
Topic: Crash and helmet
Replies: 329
Views: 22895

Re: Crash and helmet

Jdsk wrote: 23 Sep 2022, 6:09pm
buryman wrote: 23 Sep 2022, 6:01pm
Jdsk wrote: 23 Sep 2022, 5:33pm
Please could you each describe the limits of the system that you are considering.
The system is the reference frame which includes all the forces and their interactions
If 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
For us ultimately the system is the Earth if we assume no interaction with anything o/s our planet.
by buryman
23 Sep 2022, 6:01pm
Forum: Helmets & helmet discussion
Topic: Crash and helmet
Replies: 329
Views: 22895

Re: Crash and helmet

Jdsk wrote: 23 Sep 2022, 5:33pm
dmrcycle wrote: 23 Sep 2022, 5:17pm
buryman wrote: 23 Sep 2022, 4:19pm Momentum is one of the fundamental conserved quantities no matter what energy conversions are taking place.
No 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.
Please could you each describe the limits of the system that you are considering.

Thanks

Jonathan
The system is the reference frame which includes all the forces and their interactions
by buryman
23 Sep 2022, 4:19pm
Forum: Helmets & helmet discussion
Topic: Crash and helmet
Replies: 329
Views: 22895

Re: Crash and helmet

mattheus wrote: 23 Sep 2022, 2:05pm
buryman wrote: 22 Sep 2022, 2:55pm Oh dear, how wrong can one be.
Would you like have to go at the "physics" above, or should we just leave it there, and hope no-one ever finds it and believes it.
Momentum is one of the fundamental conserved quantities no matter what energy conversions are taking place.
by buryman
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.
by buryman
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.
by buryman
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.
by buryman
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.