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[Chook]

QUOTE(puckSR @ Apr 5 2006, 11:28 PM)

right so......

F= dp/dt
 = d(mv)/dt

so....you were wrong...glad we cleared that up

[jha'dhur]

QUOTE(Chook @ Apr 15 2006, 06:33 PM)

The reason Nasa uses those equations is that it can be simplified becuase of the mass lost directly from the object.  Most objects of constant mass can use the F=ma equations.  Also yeah hear, get some webspace and stop hotlinking pictures.  Also where do you work at?

The reason individuals concerned with physics use this equation is:

#1) What object/vehicle/animal/anything that you know of on gods green earth or the heavens has a constant acceleration or an perpetual increasing equation.

(i.e. the 2nd law is always valid)

The reason I even introduced the whole rocket thing because when I first approached the problem as a freshman I went straight to Newtons 2nd law, which is wrong.

IT WAS A SET UP, I dont have an ego to be served, and I usuallly dont ask questions for which I dont know answer.

#2) It is the only what that you can mathematically resolve the forces on a body(with a = 0)
*****************************************************************************

F(g) = mg

Says the only force acting on the object is gravity. (i.e. freefall)

g = 9.8 m/sec^2 translates to an object in freefall on earth, or the ball drop equation.

QUOTE(Chook @ Apr 15 2006, 06:33 PM)

Also yeah hear, get some webspace and stop hotlinking pictures.  Also where do you work at?

When you cease to be a moron, PUCK/CHOOK/NUTTY PROFFESSOR

This is my last post to you cack drips

[PhatIrishBastard]

F(net) = m*a (Newton's 2nd Law)

Is not the same expression as

F = ma(g) a derivation of Newtons 2nd Law that describes a specific class of problems.

F = mg states the only force acting on this object is gravity.

What it boils down to is you are playing you semantics game once again.

It is clear that an object with a constant velocity (i.e. a = 0) will exert a force on another object it strikes. You and your boyfriend (Vader) can yell F = 0, until you are blue in the face but I bet neither one of you would place your dense craniums in front of a vehicle moving towards you to test that theory.

Thanks CORKY, you have provided all of us with some great laughs.

[lordvader129]

QUOTE

It is clear that an object with a constant velocity (i.e. a = 0) will exert a force on another object it strikes.

its also clear that A will no longer = 0 (for either object) if a collision occurs, the point is jha'dur never asked for the force of a collision, just net force for an object with constant velocity......0

[jha'dhur]

QUOTE(puckSR @ Apr 17 2006, 08:41 PM)

A lot of kids read this forum...teenagers in high school taking physics...
I dont want them to be "challenged" because they read that F=ma is not accurate...
or that momentum is the same as force
or that the derivative of a constant isnt 0
or that F(g)=mg models motion...which it doesnt dumbass

LMAO

[jha'dhur]

QUOTE(puckSR @ Apr 17 2006, 11:00 PM)

Awwwww....jha'dhur found another picture

[jha'dhur]

QUOTE(puckSR @ Apr 18 2006, 04:18 AM)

a picture is worth a thousand words....
and when your lack of knowledge leaves you speechless....
I guess you think you can make up for it with a picture....

LOL....
So tell us again how it requires constant force to travel at constant velocity...
LOL....

Wait, wait, wait...i know....drag....LMAO.....
What was your major in college...business?
It sure as hell wasnt nuclear physics.....LOL
or anything that required an intricate understanding of mathematics...

Of course I might be wrong....you may just have a problem realizing that laws are based on simple situations...
the complex situations involve several laws acting at once....
that whole idea may just be beyond you...

[Chook]

QUOTE(jha'dhur @ Apr 15 2006, 06:39 PM)

This is my last post to you cack drips

You are a real idiot, and what do you have against Texans?  Puck still thinks that there is hope for you, but i think that you are a real nutjob and have no hope of a descent future.  None of these examples on "god's green earth" follow any of your examples also.  These are all simplifications because we do not include minor contributers to the system to avoid confusing people like you, but I am sorry for we failed.

[PhatIrishBastard]

QUOTE(Chook @ Apr 21 2006, 12:48 AM)

You are a real idiot, and what do you have against Texans?  Puck still thinks that there is hope for you, but i think that you are a real nutjob and have no hope of a descent future.  None of these examples on "god's green earth" follow any of your examples also.  These are all simplifications because we do not include minor contributers to the system to avoid confusing people like you, but I am sorry for we failed.

Actually I am the one that doesnt care for you hillbillies.

[throwingks]

QUOTE(jha'dhur @ May 5 2006, 10:06 PM)

Question:

If I throw a baseball from center fiels to 2nd bases, and it hits you in the jaw, Will the ball have enough force to break your jaw.

The possible answers to that question illustrate why you should not take COCK to seriously.

I think that you would agree the ball would strike you with some force, although it is not accelerating or traveling at a constant velocity.

There are many individuals that are masters of their own opinions and many reside here, which is probably one of the reasons I dont visit as often.

Good Luck

 

The common sense answer is yes. There is a force exerted on your face. The confusion lies in the original question. There is no longer force needed to keep the ball in motion as it is travelling through the air. As soon as it hits your face the force used to start the motion of the ball is then transferred to your face and it is no longer with the ball. That is why the ball stops moving.

[jha'dhur]

QUOTE(throwingks @ May 6 2006, 09:20 AM)

The common sense answer is yes. There is a force exerted on your face. The confusion lies in the original question. There is no longer force needed to keep the ball in motion as it is travelling through the air. As soon as it hits your face the force used to start the motion of the ball is then transferred to your face and it is no longer with the ball. That is why the ball stops moving.

COMMON sense, WTF is that, it is not allowed here..

LMAO

[puckSR]

OMFG...please...for the sake of our children and our national security....tell me your just a janitor at a nuclear facility......

You remember your entire comment about drag......
drag is a force exerted on the ball as it travels through the air right?
Ok....so does the ball slow down, stay the same speed, or go faster....

It slows down as it travels through the air.....
why?
Because there is a force due to drag acting on the ball...
however...there is no force "pushing" the ball......so
the ball slowly "accelerates in reverse" or decelerates.....
When it hits your face...it stops......and your face bears the brunt of that force...

Lets pretend you were in outerspace...when the ball hit your face...you would actually start moving....and you wouldnt be able to stop yourself....

Show me an equation that calculates the force a ball travelling through the air "has".....
You can calculate how much force the ball exerts on your face...but as everyone has pointed out to you...the ball is changing speed....(acceleration)....

Find an equation that tells us how much force the ball has without hitting something.....
go ahead....ill give you the rest of your natural life.....
the ball has momentum...but momentum isnt force......

You can also calculate the drag force and gravitational force on the ball.....
but those are trivial forces...not nearly enough to "break your jaw"....so where does that force come from?
The ball must "have force".?
The only thing that "has force" is a damn Jedi....
Everything and everyone else exerts force.....or applies force....or resists force....

[jha'dhur]

QUOTE(puckSR @ May 6 2006, 10:13 AM)

Find an equation that tells us how much force the ball has without hitting something.....
go ahead....ill give you the rest of your natural life.....

Newtons 2nd law

m dv/dt = F(m){center fielder arm strength} - F(d){Drag Force} - F(g){Mass * gravity}


 

[jha'dhur]

QUOTE(puckSR @ May 6 2006, 03:03 PM)

Hmmm  F(m)?
Center Fielders arm strength?
Do you mean to say the force at which the center fielder throws the ball?
If we really want to argue semantics...I will allow that Drag and Gravity are acting against the center fielder's throw....
However....once the ball leaves the center fielder's hand(remember my condition about hitting or touching anything)...the center fielder quits putting force on the ball....once it leaves his hand...it is travelling at its maximum velocity...
Why did the center fielder exert force on the ball?
Because he was accelerating the ball....

Ok....so lets break this down
step by step

Step 1:
Center fielder picks up ball and throws it...
The center fielder exerts a force on the ball...thats why the constant mass ball accelerates.
The center fielder's body is subject to drag, gravity, and other frictions......

Step 2:
Ball is travelling through the air...
It is decelerating because of the force due to drag on it as it travels
No force, however, is "pushing" the ball....

Step 3:
Ball collides with other player....
They player exerts a force against the ball to cause it to stop....
The ball exerts an equal force against the player when it is stopping
The force exerted by both is equal to mass time the deceleration.
This is why the force is stronger if the player "stabs" forward at the ball and weaker if he lets his glove swing back while he catches the ball.....

While the ball travels through the air during step 2....
It has momentum "pushing" it forward....but no actual force "pushing" it...
Momentum...in all honesty is not "pushing" the ball...
The ball is simply moving instead of not moving......
Newton's 1st Law....an object in motion tends to stay in motion....

The problem you seem to have jha'dhur is this:
The ball has force upon it that initially moves it
The ball exerts force when it strikes the player at the other end of the field
Why doesn't the ball have force while it is travelling through the air?(This is your argument correct?)

The basic misunderstanding seems to be your definition of force....
Force describes an interaction....it isnt an inherent property.
The ball can have velocity, momentum, energy, etc.....because those are all properties of the ball
The ball doesnt have force....force is simply a description of its interaction with other objects
Force due to drag is interaction with the air
Force due to gravity is interaction with another mass's gravitational field
Force due to the "outfielder" is an interaction between his arm and the ball...

I seriously hope you understand this time....Im honestly beginning to believe that your either too stupid or too stubborn to understand....either that or your just joking around....

You wrote all this bullshit, and in the end doesnt prove a thing , or even make a coherent point.

The force imparted on the ball by the player can be measured "intially" by the mass of ball and its acceleration of the ball at the release from thrower.

F(arm) = m(ball) a(thrower)

You arent a ENGINEER, ohh let me guess you must attend some BOGUS state school down in Lubbock taught by immigrants.

Explains alot.

[jha'dhur]

QUOTE(puckSR @ May 6 2006, 09:18 PM)

The ball doesnt "have" force...
it will exert force once it reaches the other player....

That is amusing I must say, periodic force HUH? Has some initial force, no intemediate force, yet has some final impact force. Intersting theory [cough] (Bullshit) [/cough]

Could you prove that mathematically, So that we all may be blessed by your superior intellect.

LMAO!!!!!!!!!!!!!!!!!!!!!!