Quoting BigRab <
[email protected]>:
>On 5 Sep, 15:55, PhilD <[email protected]> wrote:
>>On Sep 5, 12:32 pm, "Clive George" <[email protected]> wrote:
>>>>[1] Heavy things fall at the same speed as lighter things:
>>>>http://www.jimloy.com/physics/galileo.htm
>>>The thing is, due to the presence of this "air", it is no longer true to say
>>>that heavy things fall at the same speed as lighter things. Trivial example
>>for pelting downhill, all other things being equal, you+bike needs to
>>be heavier to achieve higher speeds.
>Surely as you increase mass then your acceleration (for a given
>force ) will be less?
"For a given force" is where you go wrong. What matters is the net force.
If I am at terminal velocity on a given hill, the net force is zero; if I
magically exchange an empty water bottle for a lead-filled one, the air
resistance does not change but the gravitational force does. The net force
is now positive; I accelerate to a higher terminal velocity.
However, generally you aren't increasing mass without changing air
resistance. The square-cube law means heavier riders tend to have a higher
ratio of mass to frontal cross section, so they descend faster. A tandem
has added an extra rider's mass almost entirely in the wind shadow of the
first rider; they descend _much_ faster. But the original question, loaded
or unloaded bike; the panniers are partly in the shadow of the legs,
partly not, probably less dense than a human rider - it's not all that
clear whether they will increase or decrease terminal velocity.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit
konomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
