Another "simple" physics question.

Speed is scaler, meaning it can be positive or negative. I.e. if you move at 5 mph forward, it would be positive. If you go back to where you came at the same speed, it would be - 5 mph. Velocity is a vector, meaning it's always positive, but changes with direction. I.e. You move at 5 mph foward and if you go back to where you came, you're moving at 5 mph in the opposite direciton.

 

Speed (a scaler) is equal to the magnitude of the velocity (a vector). Velocity has both a magnitude (=speed) and direction. Speed cannot be positive or negative, it is then a velocity, as a direction is defined. It is an absolute value.

 

Personally I think the Ferris wheel's circular motion is inconsequential compared to it's current motion away from the Universes Big Bang point.

Whether it is accelerating or steady depends on what you believe about what will happen to the universe...Big crunch? Steady State? or Constant Expansion?

 

This is an example of scientific/engineering/math language assigning an extended meaning to a word beyond everyday usage. So yes, the definition to a physicist is not the same as the definition in everyday usage. For example, the meaning of "set" or "group" to a mathematician would be very different than their meaning to the average person.

 

or an example of the evolution of the english language as the physics/engineering usages were used less and less, conversational english dropped the less-used parts

just speculating here


regardless, given that this is a physics question one might be inclined to consult a physic/engineering glossary for definitions of the terms. online exmples of such glossaries are easily found with a little help from google

 

Threads like this make me laugh.

 

I really wish I was on fchat when I took physics. I would have just posted the questions and let you guys do the work instead of having a kid in my class do it for me

 

I understand that. As long as I am moving away from center I am obviously accelerating.

If I maintain a CONSTANT distance from center (during steady rotation) then where would I be accelerating to? Why would changing direction of my velocity impart acceleration (an increase of speed [acceleration means to increase speed])?.

(loaded question, I just had a two hour discussion with an engineer about this and it seems to boil down to terminology and established concepts.)

 

And why is that?

 

Main Entry: ro·ta·tion
Pronunciation: rO-'tA-sh&n
Function: noun
1 a (1) : the action or process of rotating on or as if on an axis or center (2) : the act or an instance of rotating something b : one complete turn : [size=+2]the angular displacement required to return a rotating body or figure to its original orientation[/size]

After reading this definition I find NOTHING that explains why changing direction would cause me to move faster (ACCELERATE) or
experience a change VELOCITY IF the rotation was constant and the distance to center remained constant.


[size=+1]Post #63 is explanation enough.[/size]but I still question the mechanics of the occurance as explained. It is not a field of thought that I explore on a regular basis. This may take time to sink in.


Keep laughing Mr Payne. We all have our strong suits. Ask me about building jet airliners sometime.

 

Art, My dad tried to explain the exact same thing on an hour long drive this afternoon. Your explanation and diagram is something I can wrap my simple understanding around. Obviously I haven't had the formal introduction to the finer points of the "dancing elements" of our Universe. Just casual perusing.

I applaud your patience. Thank you.
DJ.

 

They do not mean EXACTLY the same thing! If you get that, rest will make more sense.

Read BMW.WilliamsF1team's post.

 

Then please refer to the post from the Websters dictionary that uses both words to describe each other. If they don't mean the same thing then all that is left is BMW's explanation. Is that IT?


VELOCITY
Main Entry: ve·loc·i·ty
Pronunciation: v&-'lä-s&-tE, -'läs-tE
Function: noun
Inflected Form(s): plural -ties
Etymology: Middle French velocité, from Latin velocitat-, velocitas, from veloc-, velox quick; probably akin to Latin vegEre to enliven -- more at WAKE
1 a : quickness of motion : SPEED <the velocity of sound> b : rapidity of movement <[my horse's] strong suit is grace & personal comeliness, rather than velocity -- Mark Twain> c : speed imparted to something <the power pitcher relies on velocity -- Tony Scherman>
2 : the rate of change of position along a straight line with respect to time : the derivative of position with respect to time
3 a : rate of occurrence or action : RAPIDITY <the velocity of historical change -- R. J. Lifton> <the narrative leaps from one frantic episode to another with impressive velocity -- James Atlas> b : rate of turnover <the velocity of money>

SPEED
Main Entry: 1speed
Pronunciation: 'spEd
Function: noun
Etymology: Middle English spede, from Old English spEd; akin to Old High German spuot prosperity, speed, Old English spOwan to succeed, Latin spes hope, Lithuanian speti to be in time
1 archaic : prosperity in an undertaking : SUCCESS
2 a : the act or state of moving swiftly : SWIFTNESS b : rate of motion: as (1) : VELOCITY 1, 3a (2) : the magnitude of a velocity irrespective of direction c : IMPETUS
3 : swiftness or rate of performance or action

According to the two above definitions SPEED and VELOCITY mean the same thing and the action thereof is also the same or is this too simplistic?.
The ONLY variable in the discussion is acceleration which is the increase of EITHER or BOTH speed and velocity.

 

You know, after all of the rhetoric, postulating, disagreements and hardheadedness on my part a few undeniable facts remain. Without fully understanding the technical aspects of everything discussed here I am still able to see it and use it in a real time, real life situation instead of testing it's theories in the controlled envoirons of a class room in the dry pages of a dry book written by a dry fossil.

A kid came by today in my old 1972 Datsun 240Z that he had just installed a 2001 Skyline R20B turbo charged engine in. This produces around 225 RWHP in a 2300 lb car. A far cry from the stock 140 or so HP at the rear wheels stock.

We took it for a ride and I experienced the loss of rear wheel traction in 3rd gear at 50 MPH. I also lost traction shifting to 4th at 60 MPH. I entered a corner at 40 MPH and tipped the throttle in about half way and executed a nice power on slide through the remainder of the corner, counter steering to compensate for the CENTRIFUGAL force..

The acceleration of this car was brutal and required hard braking on numerous occasions.

Today I induced and experienced ACCELERATION to high rates of SPEED and DEACCELERATION. I "fishtailed" while ACCELERATING exacerbated by the GYROSCOPIC forces caused by the spinning rear wheels.

Throughout the entire time I did not once think of any of the words in the previous paragraph or what the car was doing from a technical standpoint. I probably didn't even use the words in the last paragraph in the right context. I know I didn't think about those neat colored diagrams that were drawn in this thread for my benefit. They wouldn't have helped me one bit sliding through the corners.

I was driving a fast car, I didn't crash it and didn't think about men on ferris wheels or merry go rounds once while I was doing it.

I had a blast today driving that car and learning it's idiocincracies. I also learned a lot from this thread as well but without the back ground some of you have I feel I am at a disadvantage as much as you would be if you had never driven something like I had today. I just spent my thousands of dollars on a different kind of "tuition"

I guess it's all relative and you know how we feel about relatives.

Cheers. DJ
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My pleasure. I'm not much of an interior guy but I am pretty good with systems.

 

You know, usually ferrarichat.com impresses me. But this and the last physics question gives me the feeling you're all a bunch of idoits

 

Centrifugal force is not a force at all, it's inertia

 

I have news for you pal. "IDIOTS" is a world wide phenomenon and some, if not most, don't even know they are one.

If I am one by some I am happy knowing that I am not by others, The important ones

 

Not directed (exclusively) at you, and all in good fun.

But seriously, the plane takes off and the wheel ain't moving!

 

The poorly phrased question, the poorly phrased responses, the continual discussion on something which has a very clear cut answer. The memories it brings back of dynamics (arguably the hardest class a 'physical' engineer has to take).