Simviation Forums

Posted: **Thu Nov 22, 2007 9:33 am**

I'm a little confused... The theme of the November Screen Shot competition is "Acceleration". I thought that acceleration was the capacity to "dig out" like a quarter-horse, not like a "thorobred" that out speeds the quarter-horse in a long race.

Hummmmmm :-? :-? :-? :-? :-? :-?

Webster:

Acceleration: Increase In Velocity: the rate at which something increases in velocity.

Speed: Rate Of Movement: the rate at which something moves or functions.

Example of speed: The jet that has to spool up, barely starts to move down the runway but eventually gets up and in time increases speed to better than the speed of sound. All speed.

Example of acceleration: The prop plane that has immediate response to the throttle, digs out, in the air at 500 feet and accelerates to a maximum of 300 Mph in seconds. All acceleration.

Now, I know that there are exceptions, but in general, isn't this true?

Something to think about. DB ::)

Posted: **Thu Nov 22, 2007 9:52 am**

Example of speed: The jet that has to spool up, barely starts to move down the runway but eventually gets up and in time increases speed to better than the speed of sound. All speed.

Example of acceleration: The prop plane that has immediate response to the throttle, digs out, in the air at 500 feet and accelerates to a maximum of 300 Mph in seconds. All acceleration.

No, and no, not all speed, and not all acceleration.

acceleration is a change in velocity, all of this is physics related and speed and acceleration are different, acceleration happens when something gains speed or loses speed.

acceleration=change in velocity/time interval also acceleration=net force/mass

now speed, or average speed may be easier, is Average speed=total distance covered/time interval

so say you want to find a final velocity for something from rest that accelerates at 80m/s^2 for 100m

vf^2= v original ^2 + 2(80) x 100

So velocity final would be 126.4 m/s so, acceleration plays a part in speed but they are not one in the same.

BTW I could have made an error, I havent done physics in a couple weeks ::)

Posted: **Thu Nov 22, 2007 12:14 pm**

A bit of over analysis in my opinion ::)

Posted: **Thu Nov 22, 2007 12:27 pm**

Example of speed: The jet that has to spool up, barely starts to move down the runway but eventually gets up and in time increases speed to better than the speed of sound. All speed.

Example of acceleration: The prop plane that has immediate response to the throttle, digs out, in the air at 500 feet and accelerates to a maximum of 300 Mph in seconds. All acceleration.

No, and no, not all speed, and not all acceleration.

acceleration is a change in velocity, all of this is physics related and speed and acceleration are different, acceleration happens when something gains speed or loses speed.

acceleration=change in velocity/time interval also acceleration=net force/mass

now speed, or average speed may be easier, is Average speed=total distance covered/time interval

so say you want to find a final velocity for something from rest that accelerates at 80m/s^2 for 100m

vf^2= v original ^2 + 2(80) x 100

So velocity final would be 126.4 m/s so, acceleration plays a part in speed but they are not one in the same.

BTW I could have made an error, I havent done physics in a couple weeks

Nerd

Just kidding Monkey^...You know I love you

Posted: **Thu Nov 22, 2007 12:30 pm**

Example of speed: The jet that has to spool up, barely starts to move down the runway but eventually gets up and in time increases speed to better than the speed of sound. All speed.

Example of acceleration: The prop plane that has immediate response to the throttle, digs out, in the air at 500 feet and accelerates to a maximum of 300 Mph in seconds. All acceleration.

No, and no, not all speed, and not all acceleration.

acceleration is a change in velocity, all of this is physics related and speed and acceleration are different, acceleration happens when something gains speed or loses speed.

acceleration=change in velocity/time interval also acceleration=net force/mass

now speed, or average speed may be easier, is Average speed=total distance covered/time interval

so say you want to find a final velocity for something from rest that accelerates at 80m/s^2 for 100m

vf^2= v original ^2 + 2(80) x 100

So velocity final would be 126.4 m/s so, acceleration plays a part in speed but they are not one in the same.

BTW I could have made an error, I havent done physics in a couple weeks

Nerd

Just kidding Monkey^...You know I love you

Nah, I'm actually barley passing the class lol

Posted: **Thu Nov 22, 2007 12:37 pm**

uurrrm i beg to differ there Acceleration= Change in SPEED (not velocity) over a givern time, velocity is speed in a givern direction and mass has NO part of the equation as that would be momentum! you are thinking of and here is how you work out acceleration = change in velovity/time or delta V over Time (s) which would give you your acceleration in the form of m/s^2

I should have explained better on what the mass does, with any object you will have a coefficient of friction, force down, force normal, and force of friction. For say a ramp with something sliding down thats where mass comes into play, you can figure the acceleration that way. Net force is the FD - FF (if I remember correctly). Using that and knowing the mass of an object you can find its acceleration assuming you have a final speed and can find a distance. Ill go look at the book because I'm basically rambling. I need to do homework anyway

Obviously that equation only works in certain instances.

uurrrm i beg to differ there Acceleration= Change in SPEED (not velocity)

It is velocity

Posted: **Thu Nov 22, 2007 1:21 pm**

anyone that did physics or maths to high school level should know that stuff.

Posted: **Thu Nov 22, 2007 2:46 pm**

Nice discussion.

I'm now looking forward to the Screenshot Competition whose subject is "Torque" ;)

Posted: **Thu Nov 22, 2007 2:55 pm**

Masternerd,

You always come through with a practicle solution. However, I read over my post and must correct one thing. Where in the examples I said "all acceleration" and "all speed" should have been "mostly acceleration" and "mostly speed". This is obvious, but I didn't catch it. Seems I'm always in a hurry for some reason or another.

Boy, we really have some physisists here, and I'm glad. I truely beleive (after my college physics) that there is a scientific answer for everything.

But still, there is a practicle way express and to answer a problem, if one should read my original post. Oh well, enough said.

Happy flying everyone and thanks for all of your comments.

DB

Posted: **Thu Nov 22, 2007 3:07 pm**

you can be travelling at Mach 10 and have zero acceleration, and you can be travelling at 10knots and have a huge acceleration! good sum up?

Posted: **Thu Nov 22, 2007 5:12 pm**

Technical term for acceleration - rate of change of speed

Posted: **Thu Nov 22, 2007 5:41 pm**

Hi Gilly and Spitfire Boy,

Two really good comments. Webster can't put it better. "ya'll" know what acceleration is.

A running hog is a good example, he digs out, goes 20 mph in one second, you can outrun him, as he is a slow runner, but try to stop him, bam!!!, your're on your nose. I say that's almost pure acceleration. Try it sometime, you won't like it!!! Ha!

Take care, DB

Posted: **Thu Nov 22, 2007 6:42 pm**

trying to stop him is nothing to do with acceleration, thats power and inertia!

Posted: **Thu Nov 22, 2007 10:59 pm**

trying to stop him is nothing to do with acceleration, thats power and inertia!

+1

Posted: **Fri Nov 23, 2007 12:39 pm**

...acceleration happens when something gains speed or loses speed.

We're getting muddled between the math and the wording. The increase is acceleration -- a speed declination would be 'decelleration'; thus a 'deceleron' on an aircraft is to slow it down.

8-)

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