How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Bill

On 22/08/2019 21:34, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?


it'd be easier to answer that with more context - eg how many pints of
what? what colour and shape were the pills? did you inhale...

--
Robin
reply-to address is (intended to be) valid

On Thursday, 22 August 2019 21:34:05 UTC+1, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Because it's easier to hold something still than to move it.

If you turned the sander off and rubbed the wood against it, the sander wouldn't be using any energy.

It's a bit like cycling - easier than walking, but actually less efficient in a purely energy sense because there's the additional weight of the bicylce to move.

Owain

On Thu, 22 Aug 2019 14:02:19 -0700 (PDT),
wrote:

On Thursday, 22 August 2019 21:34:05 UTC+1, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Because it's easier to hold something still than to move it.

If you turned the sander off and rubbed the wood against it, the sander wouldn't be using any energy.

It's a bit like cycling - easier than walking, but actually less efficient in a purely energy sense because there's the additional weight of the bicylce to move.

Owain
Mass.

If the sander were made of polystyrene you would be more in agreement
with Newton.

AB

Bill Wright wrote :
How come it needs much less effort to hold an electric sander against the
work than it does to do the work manually?

Because you only have to steady it a little and aim it at the work, the
inertia of the weight of the sander, will help you to keep the sander
steady, forcing the plate with the sandpaper to move.

On 22/08/2019 21:34, Bill Wright wrote:

How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Depends rather on if you turn the sander on... if you hold it against
*and* waggle it round in small orbits, I am going to guess it will be
harder!


--
Cheers,

John.

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On Thu, 22 Aug 2019 14:02:19 -0700 (PDT), wrote:

It's a bit like cycling - easier than walking, but actually less efficient in a purely energy sense because there's the additional weight of the bicylce to move.

But you are sitting, or even recumbent on a bicycle. In physics standing around
doesn't use energy, but it does in people.


Thomas Prufer

I would have thought it was obvious. All your energy is concentrated in
mostly one direction. The friction against the job face only has to be
resisted,not generated as well.
Brian

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"Bill Wright" wrote in message
...
How come it needs much less effort to hold an electric sander against the
work than it does to do the work manually?

Bill

So you need the sanding equivalent of freewheeling downhill.
Brian

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wrote in message
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On Thursday, 22 August 2019 21:34:05 UTC+1, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Because it's easier to hold something still than to move it.

If you turned the sander off and rubbed the wood against it, the sander
wouldn't be using any energy.

It's a bit like cycling - easier than walking, but actually less efficient
in a purely energy sense because there's the additional weight of the
bicylce to move.

Owain

Yes inertia does have a roll to play, if it did no then hammers would be
useless for banging nails in.
Brian

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"Archibald Tarquin Blenkinsopp ESQ [IRL]" wrote in
message ...
On Thu, 22 Aug 2019 14:02:19 -0700 (PDT),
wrote:

On Thursday, 22 August 2019 21:34:05 UTC+1, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Because it's easier to hold something still than to move it.

If you turned the sander off and rubbed the wood against it, the sander
wouldn't be using any energy.

It's a bit like cycling - easier than walking, but actually less efficient
in a purely energy sense because there's the additional weight of the
bicylce to move.

Owain
Mass.

If the sander were made of polystyrene you would be more in agreement
with Newton.

AB

On 22/08/2019 21:34, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Bill
because in theory holding something in place does no work at all


Work = force times distance.

All force, no distance

An infintely large infinitely strong helicopter could hover with no
power input.





--
€œThere are two ways to be fooled. One is to believe what isnt true; the
other is to refuse to believe what is true.€�

€”Soren Kierkegaard

On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance

An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades. The
work is proportional to the torque on the rotor shaft and the number of
revolutions.

On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades. The
work is proportional to the torque on the rotor shaft and the number of
revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.


--
€œwhen things get difficult you just have to lie€�

€• Jean Claud Jüncker

On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades.
The work is proportional to the torque on the rotor shaft and the
number of revolutions.

An infintely large rotor turns at zero RPM

an infinitely large rotor will at best generate a finite lift since
there is only a finite amount of air in which to perform. That lift is
less than required to overcome the infinite gravitational attraction to
the Earth.

There are no revolutions.



--
Cheers,

John.

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On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades.
The work is proportional to the torque on the rotor shaft and the
number of revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.



if it is also an infinitely heavy helicopter I'd like to see the proof

if it isn't infinitely heavy why bother with rotors when you could just
use cavorite?


--
Robin
reply-to address is (intended to be) valid

On 23/08/2019 13:17, Robin wrote:
On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades.
The work is proportional to the torque on the rotor shaft and the
number of revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.



if it is also an infinitely heavy helicopter I'd like to see the proof

if it isn't infinitely heavy why bother with rotors when you could just
use cavorite?


The point is that it takes no energy to hover since no potential energy
is lost or gained.

It takes energy to accelerate an air mass downwards to generate the
momentum change that provides the lift.

But energy is 1/2mV^2 whereas momentum is mV so as m tends to infinity V
tends to zero for the same lift

That is, an infinitely large rotor.

If you google the man powered helicopter you will see it has a rotor the
size of a tennis court


--
How fortunate for governments that the people they administer don't think.

Adolf Hitler

On 23/08/2019 08:14, The Natural Philosopher wrote:
On 22/08/2019 21:34, Bill Wright wrote:
How come it needs much less effort to hold an electric sander against
the work than it does to do the work manually?

Bill
because in theory holding something in place does no work at all


Work = force timesÂ* distance.

All force, no distance

An infintely large infinitely strongÂ* helicopter could hover with no
power input.






With infinite gravity so it wouldn't hover.

On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with no
power input.

Not so. It's having to generate lift with the rotating rotor blades. The
work is proportional to the torque on the rotor shaft and the number of
revolutions.

Its OK TNP lies about understanding physics.

On 23/08/2019 18:53, The Natural PhiThe lift with zero rpm is still
zero.losopher wrote:
On 23/08/2019 13:17, Robin wrote:
On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with
no power input.

Not so. It's having to generate lift with the rotating rotor blades.
The work is proportional to the torque on the rotor shaft and the
number of revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.



if it is also an infinitely heavy helicopter I'd like to see the proof

if it isn't infinitely heavy why bother with rotors when you could
just use cavorite?


The point is that it takes no energy to hover since no potentialÂ* energy
is lost or gained.

ItÂ* takes energy to accelerate an air mass downwards to generate the
momentum change that provides the lift.

But energy is 1/2mV^2 whereas momentum is mV so as m tends to infinity V
tends to zero for the same lift

That is, an infinitely large rotor.

Consider a helicopter with rotors with radius r=10m turning at 0 rpm.
Lift generated is zero. OK?

Double the radius to 20m. Lift generated is still zero. OK?

Let the radius r tend to infinity. The lift if rpm is zero is still
zero. Oh dear!

--
Robin
reply-to address is (intended to be) valid

On 23/08/2019 21:18, Robin wrote:
On 23/08/2019 18:53, The Natural PhiThe lift with zero rpm is still
zero.losopher wrote:
On 23/08/2019 13:17, Robin wrote:
On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with
no power input.

Not so. It's having to generate lift with the rotating rotor
blades. The work is proportional to the torque on the rotor shaft
and the number of revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.



if it is also an infinitely heavy helicopter I'd like to see the proof

if it isn't infinitely heavy why bother with rotors when you could
just use cavorite?


The point is that it takes no energy to hover since no potential
energy is lost or gained.

ItÂ* takes energy to accelerate an air mass downwards to generate the
momentum change that provides the lift.

But energy is 1/2mV^2 whereas momentum is mV so as m tends to infinity
V tends to zero for the same lift

That is, an infinitely large rotor.

Consider a helicopter with rotors with radius r=10m turning at 0 rpm.
Lift generated is zero. OK?

No.
It isnt

Double the radius to 20m.Â* Lift generated is still zero.Â* OK?
No. It isn;t


Let the radius r tend to infinity.Â* The lift if rpm is zero is still
zero.Â* Oh dear!

No, it isn't

Think 'infinite parachute'



--
"The most difficult subjects can be explained to the most slow witted
man if he has not formed any idea of them already; but the simplest
thing cannot be made clear to the most intelligent man if he is firmly
persuaded that he knows already, without a shadow of doubt, what is laid
before him."

- Leo Tolstoy

On 23/08/2019 21:18, Robin wrote:
On 23/08/2019 18:53, The Natural PhiThe lift with zero rpm is still
zero.losopher wrote:
On 23/08/2019 13:17, Robin wrote:
On 23/08/2019 11:17, The Natural Philosopher wrote:
On 23/08/2019 10:34, Mike Clarke wrote:
On 23/08/2019 08:14, The Natural Philosopher wrote:

All force, no distance
An infintely large infinitely strongÂ* helicopter could hover with
no power input.

Not so. It's having to generate lift with the rotating rotor
blades. The work is proportional to the torque on the rotor shaft
and the number of revolutions.

An infintely large rotor turns at zero RPM

There are no revolutions.



if it is also an infinitely heavy helicopter I'd like to see the proof

if it isn't infinitely heavy why bother with rotors when you could
just use cavorite?


The point is that it takes no energy to hover since no potential
energy is lost or gained.

ItÂ* takes energy to accelerate an air mass downwards to generate the
momentum change that provides the lift.

But energy is 1/2mV^2 whereas momentum is mV so as m tends to infinity
V tends to zero for the same lift

That is, an infinitely large rotor.

Consider a helicopter with rotors with radius r=10m turning at 0 rpm.
Lift generated is zero. OK?

Double the radius to 20m.Â* Lift generated is still zero.Â* OK?

Let the radius r tend to infinity.Â* The lift if rpm is zero is still
zero.Â* Oh dear!



Infinite large chopper with infinite mass, above an infinite planet with
infinite mass, gives infinite force so will result in infinite
acceleration towards the planet. So you need infinite RPM to contract it
for the infinitesimal time it takes to get to light speed then you need
different physics.

TNP will now explain it all using his infinite brain!

On Fri, 23 Aug 2019 20:15:39 +0100
"dennis@home" wrote:

With infinite gravity so it wouldn't hover.

As it's the most massive object in the universe it doesn't need to
hover, Galaxies, however, would be quite keen to maintain their
distance from it.

On 25/08/2019 21:00, Rob Morley wrote:
On Fri, 23 Aug 2019 20:15:39 +0100
"dennis@home" wrote:

With infinite gravity so it wouldn't hover.

As it's the most massive object in the universe it doesn't need to
hover, Galaxies, however, would be quite keen to maintain their
distance from it.


the infinite planet is more massive, but difficult to prove.