Jump to content

Silly Picture Thread.


Phil Perry

Recommended Posts

2 hours ago, facthunter said:

and W=Mg

Holy Newtonian Physics, Batman! Are you trying to :stirrer: , Nev?

The correct formula when talking about force when the Frame of Reference is on the surface of the Earth is: F = ma.

 

Note the use of the lower case "m". The uppercase "M" is used in astrophysics when the Field of Reference is  a planetary system or bigger. 

 

The lowercase "a" is used for the acceleration resulting from the application of a Force on a "small" object, like a push on a car or a throw of a ball. The lowercase "g" is used when the cause of the acceleration is the gravitational attraction of the Earth (9.81 m/s/s)

 

Now for the pot stirrer. "W" is not used in physics for "Force". It can be used as shorthand for "work", where Work = Force x distance. However, in the context of Nev's post we can infer that he means "W" to represent "weight", in a non-scientific colloquial sense. "Weight" is a particular class of Force. It is the force created when a "small m" mass is accelerated by a planetary bodies gravitational acceleration, "g".

 

I've debated the difference between "weight" and "mass" and have reached a consensus view that both terms related to the number of atoms in an object, but for the non-labcoated "weight" is the understandable, day-to-day term.

 

And just for a bit of trivia, here's an explanation of the difference in astrophysics between "M" and "m"

 

 

 

 

 

 

  • Informative 1
Link to comment
Share on other sites

Sorry Nev, but in scientific shorthand, uppercase G is used to express the constant which has the value of 6.674 30 x 10-11 m3 kg-1 s-2This constant is called the Universal Gravitational Constant, and does not change throughout the Universe. Lowercase g is used to express the acceleration of a mass due to the mass of the Earth. The force of gravity with which an object is attracted to the earth is given by:

Gravitational Force | Definition, Formula & Examples - Video & Lesson  Transcript | Study.com

 

 

 

 

 

  • Informative 1
Link to comment
Share on other sites

I agree that in aviation the term "G" is used as jargon - trade talk. It is used to describe the acceleration component of a Force calculation and is used when comparing forces acting on a structure.

 

For example, the force acting on a wing spar of an aircraft stationary on the ground at Mean Sea level is given by mass x acceleration due to gravity (9.81 m/s/s, or 32 ft/s/s). However, put that plane into a dive and pull up sharply and the force is a lot more. The mass remains the same, so the acceleration must increase. If, say, the calculated force in the pull out is four times as much as the force of the plane sitting on the ground, then the acceleration must increase. The ratio between the pull out force and the "on ground" force would be 4:1. If the wing spar can take that amount of force, in trade jargon we say that the wing spar will handle 4Gs.

1 hour ago, facthunter said:

Life doesn't have to be as esoteric and complex as you make it

I realise that this forum isn't meant to be as technical as those on the sister site, but there are few here who don't possess a degree of specialised knowledge in relation to aviation. Therefore it seems OK to be somewhat esoteric (intended for or likely to be understood by only a small number of people with a specialized knowledge or interest). As for complexity, The force equation used here is about as simple as you can get. We could start analysing forces with Three Dimensional geometry.

  • Informative 1
Link to comment
Share on other sites

Nev, you should know better than to argue with Professor OME. 

 

As regards Indigo Nev, the scientists claim that Indigo is no longer a colour - who are we but plebs, to argue against their superior understanding?

 

QUOTE:

"The colour “indigo” refers to a blue-purple colour that many people can't actually distinguish from blue or purple."

 

Edited by onetrack
  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...