Physical meaning of a Metre-Second? [or (Kg · s) or (N · s) ]

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The discussion explores the physical meaning of units like "metre-second" (m·s) and how they relate to other measurements such as dynamic viscosity and momentum. Participants note that while "metres per second" (m/s) is easily understood, the concept of a "metre-second" lacks a clear physical interpretation. Examples are provided, including dynamic viscosity expressed as kilograms per metre-second (Kg/m·s) and momentum as kilogram-metres per second (kg·m/s), which equate to Newton-seconds (N·s). The conversation also touches on how these units can represent physical phenomena, such as impulse, which is the product of force and time. Overall, the thread highlights the complexity and sometimes abstract nature of certain physical units.
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We all understand what metres PER second (m/s) physically means... but,
What I was wondering was what does a 'metre-second' actually mean? Or does it have a physical meaning at all!

As an example:

If we take the units for Dynamic viscosity we have:

Kilogram per metre second ( Kg / m.s )

On a side note, in relation to my above example:
The SI physical unit of dynamic viscosity is the pascal-second (Pa·s), which is identical to
Kg. m-1.s-1 = Kg / (m s)


Another example, of a similar type, would be the standard unit of momentum, which is:
Kilogram-metre per second (kg · m/s or kg · m · s-1 ) which in SI units is equal to Newton-second (N · s)

In this example we have both a Kilogram-metre and, in SI, a Newton-second!
I can easily conceptualise the idea of, say, 1 Metre every 1 Second (m/s) but I am finding it hard to conceptualise this concept!

How exactly could one have, in the physical world, a metre-second (m · s), kilogram-metre (Kg · m) or Newton-second (N · s)?
 
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If you could snort a white powdery substance from the surface of a mirrored conveyer belt moving at a fixed speed using a stationary rolled up piece of currency with a diameter measured in meters and had a certain number of seconds to do so, the "meter second" could be used as a relevant measure.
 
jbriggs444 said:
If you could snort a white powdery substance from the surface of a mirrored conveyer belt moving at a fixed speed using a stationary rolled up piece of currency with a diameter measured in meters and had a certain number of seconds to do so, the "meter second" could be used as a relevant measure.

:smile: :smile:


CF.Gauss said:
We all understand what metres PER second (m/s) physically means... but,
What I was wondering was what does a 'metre-second' actually mean? Or does it have a physical meaning at all!

As an example:

If we take the units for Dynamic viscosity we have:

Kilogram per metre second ( Kg / m.s )

On a side note, in relation to my above example:
The SI physical unit of dynamic viscosity is the pascal-second (Pa·s), which is identical to
Kg. m-1.s-1 = Kg / (m s)


Another example, of a similar type, would be the standard unit of momentum, which is:
Kilogram-metre per second (kg · m/s or kg · m · s-1 ) which in SI units is equal to Newton-second (N · s)

In this example we have both a Kilogram-metre and, in SI, a Newton-second!
I can easily conceptualise the idea of, say, 1 Metre every 1 Second (m/s) but I am finding it hard to conceptualise this concept!

How exactly could one have, in the physical world, a metre-second (m · s), kilogram-metre (Kg · m) or Newton-second (N · s)?

Never used metre-second but for something like the N*s, it would be the force acting over a period of time such that the Impulse = Force*time

For something like kg-m, this could be something like a mass acting a distance. For example, if you have a shaft with an unbalance in it (center of rotation does not coincide to where the mass acts), you quantify the unbalance as a mass-eccentricity.

Mass eccentricity me = mass*distance, usually given in gram-cm or some unit like that.
 
rock.freak667 said:
Never used metre-second but for something like the N*s, it would be the force acting over a period of time such that the Impulse = Force*time

would the force acting over a period of time not be Newtons per second ( N/s )?
 
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CF.Gauss said:
would the force acting over a period of time not be Newtons per second ( N/s )?

That would give you the rate of change of force. A typical Force-time graph looks like this:

09_03Figure.jpg



The area under the graph gives the impulse which is the same as the change in momentum.
 
jbriggs444 said:
If you could snort a white powdery substance from the surface of a mirrored conveyer belt moving at a fixed speed using a stationary rolled up piece of currency with a diameter measured in meters and had a certain number of seconds to do so, the "meter second" could be used as a relevant measure.
Very good!
I thought of a tunnel's price (tunnel length multiplied time of realization) but you beat me...
 
Assume that this is a case where by sheer coincidence, two sources of coherent single-frequency EM wave pulses with equal duration are both fired in opposing directions, with both carrying the same frequency and amplitude and orientation. These two waves meet head-on while moving in opposing directions, and their phases are precisely offset by 180 degrees so that each trough of one wave meets with the crest of the other. This should be true for both the electric and magnetic components of...

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