Spring scales all have inaccuracies. However, it's not a guarentee that the most accruate part of the measure will start at zero. It might even be that the scale is most accurate at the weight of the bucket and water. Either way, the error will be too small to fret over.

 

Spring scales all have inaccuracies. However, it's not a guarentee that the most accruate part of the measure will start at zero. It might even be that the scale is most accurate at the weight of the bucket and water. Either way, the error will be too small to fret over.

Well there is one way to find out for certain.

I have always found that there is a REASON why people do what they do and all that needs to be done is ask the guy selling bait to weigh the fish his way and then place the bucket with water on the scale...read the weight and then put the fish in the bucket on the scale read that weight and subtract the first reading from the second to give you the weight of the fish.

First...not to **** him off...let him place the bucket and water on the scale first and get that reading before he zero's out...then let him add the fish to get his reading of fish weight...remove the bucket and zero out the scale...place the bucket back on and take that reading...as to not have him go through too many changes.

I am willing to bet there is a significant difference.

Split Infinity

 

Tracecom.....
Louisiana.....South of Interstate 10
The Louisiana State motto is...."thank God for Mississippi"....

 

I am willing to bet there is a significant difference.

Split Infinity

Depends on what you mean by significant. Most than likely the scale is most inaccurate from 0-1lb, so the method being used is the best way to do it.

 

First...not to **** him off...let him place the bucket and water on the scale first and get that reading before he zero's out...then let him add the fish to get his reading of fish weight...remove the bucket and zero out the scale...place the bucket back on and take that reading...as to not have him go through too many changes.

I am willing to bet there is a significant difference.

Split Infinity

Most likely since the scale was zeroed when another object was on the scale so the reading of the bucket and water is way off to begin with.

 

Most likely since the scale was zeroed when another object was on the scale so the reading of the bucket and water is way off to begin with.

Probably so.

Split Infinity

 

dthx - Did I miss something? Did you mention this was a spring scale, or a balance type, or is it electronic ?

 

It's electronic....a flat plate on a pretty good sized device ...and a readout below....
Its easy for the guy to zero out the scale...
Im sorry I got this thing started.....
Wont do it again.
D.

 

Im sorry I got this thing started.....
Wont do it again.
D.

Don't be sorry. We argue on here all the time.

 

It's electronic....a flat plate on a pretty good sized device ...and a readout below....
Its easy for the guy to zero out the scale...
Im sorry I got this thing started.....
Wont do it again.
D.

I think you should do it again. After all, it keeps our brain cells kicking instead of vegetating.

 

I haven't been repeating myself here because my explanation of the system boundaries method is so all inclusive that it doesn't need to be repeated enough times to make it true. The only surprise to me is that this conversation is still happening, long after the definitive answer has been given. Tare-ing out the weight of the bucket and water is a time honored tradition because it works.

Another way to do this thought experiment is to consider the inertia of the fly. Let's define our boundaries as the outer space example (to eliminate atmospheric interference). Energy is required to accelerate the space craft. The mass of the fly will have to be included in the math required to find the amount of energy needed to accelerate the spacecraft with a fly inside it. The beauty of a good mental experiment is that it doesn't matter if the scale is made with springs, piezo elements, a stick with notches in it, or Harry Potter's magic wand. Which device is used to measure the energy is irrelevant. Pretending the measuring device matters is only a way to cloud the issue in hopes that somebody will be fooled into thinking it does matter.

Your minnow merchant is treating you fairly. You are getting a pound of fish for the price that is posted on the wall at the bait shop

ps, I caught the Archimedes reference in the Brownout post. Sneaky is good

 

Your minnow merchant is treating you fairly. You are getting a pound of fish for the price that is posted on the wall at the bait shop

But not if they are being sold in a Gravity Well or Singularity. How do we Know what the quality of the Quantum is for those fish?

 

I haven't been repeating myself here because my explanation of the system boundaries method is so all inclusive that it doesn't need to be repeated enough times to make it true. The only surprise to me is that this conversation is still happening, long after the definitive answer has been given. Tare-ing out the weight of the bucket and water is a time honored tradition because it works.

Another way to do this thought experiment is to consider the inertia of the fly. Let's define our boundaries as the outer space example (to eliminate atmospheric interference). Energy is required to accelerate the space craft. The mass of the fly will have to be included in the math required to find the amount of energy needed to accelerate the spacecraft with a fly inside it. The beauty of a good mental experiment is that it doesn't matter if the scale is made with springs, piezo elements, a stick with notches in it, or Harry Potter's magic wand. Which device is used to measure the energy is irrelevant. Pretending the measuring device matters is only a way to cloud the issue in hopes that somebody will be fooled into thinking it does matter.

Your minnow merchant is treating you fairly. You are getting a pound of fish for the price that is posted on the wall at the bait shop

ps, I caught the Archimedes reference in the Brownout post. Sneaky is good

You mean if I am with Bugs Bunny in a Falling Fast Elevator....just when it hits the bottom...I can't just Jump Up and Out? LOL!

Split Infinity...p.s...Don't forget the Air Brakes on a Crashing Airplane!

 

Ok....physics men.....or women as the case may be....
Riddle me this...now that you mention it.
Say...I am in elevator and the elevator is decending at the usual rate.
So I have the same velocity as the elevator....I got that.
But then I jump up into the center of the elevator...
When I reach the top of my jump and start to come down ...I'm weightless, right?
So the "boundries" conception is false, right....because at that point in time....I do not add to the elevators weight, right"

 

By the way.....what happens at that moment...when kinetic energy is changed to potential energy?
Being true to the conversation of energy concept....what is given off ...heat...light....what....cause when you change an energy form....somethings got to give....correct.....?
There has to be less kinetic energy than potential energy....does gravity eat the diff up in some way....
Cause when I hit the bottom of the elevator...I would impact with less force than it took to get up to the top of my jump...so where does the energy go....?
Just a thought provoking little snippet.

 

Ok....physics men.....or women as the case may be....
Riddle me this...now that you mention it.
Say...I am in elevator and the elevator is decending at the usual rate.
So I have the same velocity as the elevator....I got that.
But then I jump up into the center of the elevator...
When I reach the top of my jump and start to come down ...I'm weightless, right?
So the "boundries" conception is false, right....because at that point in time....I do not add to the elevators weight, right"

For the time that you leap into the air you do not apply weight to the elevators floor and the cables that hold and move the elevator have less stress and tension upon them.

The moment your feet fall back to the floor your weight plus the additional foot pounds of applied force from the impact of your fall will stress the cables beyond what just your weight standing in the elevator would generate.

Split Infinity

 

By the way.....what happens at that moment...when kinetic energy is changed to potential energy?
Being true to the conversation of energy concept....what is given off ...heat...light....what....cause when you change an energy form....somethings got to give....correct.....?
There has to be less kinetic energy than potential energy....does gravity eat the diff up in some way....
Cause when I hit the bottom of the elevator...I would impact with less force than it took to get up to the top of my jump...so where does the energy go....?
Just a thought provoking little snippet.

You have to place some parameters upon that question for you to get your specific desired answers...as I can see several ways of answering your questions.

Split Infinity

 

Well, I appreciate your post...and I understand it...its a given...
But it doesnt get to the point of my question.
First I flex my legs and impart a force into the floor of the elevator which stresses the cables, etc...
The force my legs generate put me up to the center of the car.
At the moment at which I stop and start to come down...Im weightless....
So I add no weight to the car.....
So the systems boundries concept explained by #12 earlier would not apply, right?
His concept explained a lot to me and helped me explain a lot to my young friend....but further thought has brought to ask the above...
Its prob. elementary you all of you...

 

Well, I appreciate your post...and I understand it...its a given...
But it doesnt get to the point of my question.
First I flex my legs and impart a force into the floor of the elevator which stresses the cables, etc...
The force my legs generate put me up to the center of the car.
At the moment at which I stop and start to come down...Im weightless....
So I add no weight to the car.....
So the systems boundries concept explained by #12 earlier would not apply, right?
His concept explained a lot to me and helped me explain a lot to my young friend....but further thought has brought to ask the above...
Its prob. elementary you all of you...

Newtonian physics would say that when you jumped you pushed the elevator away from you (causing more strain on the cables). All the time you are not touching the floor of the elevator, you impart no addition strain on the cables. The cables only have the weight of the elevator on them. When you hit the floor, you again cause additional strain on the cables.
As an example:
Starting position: 500 N on the cable
Jumping up: 700 N on the cable
Off the floor: 300 N on the cable
Landing on the floor: 700 N on the cable
Standing on floor: 500 N on cable

 

Well, I appreciate your post...and I understand it...its a given...
But it doesnt get to the point of my question.
First I flex my legs and impart a force into the floor of the elevator which stresses the cables, etc...
The force my legs generate put me up to the center of the car.
At the moment at which I stop and start to come down...Im weightless....
So I add no weight to the car.....
So the systems boundries concept explained by #12 earlier would not apply, right?
His concept explained a lot to me and helped me explain a lot to my young friend....but further thought has brought to ask the above...
Its prob. elementary you all of you...

There lies a difference in say...jumping up in an air filled elevator...and swimming up from a water filled elevator.

Even though the total mass of a closed elevator is the combined mass of the elevator and everything inside...the mass of the air is so slight that by jumping up a person will remove their weight from the total weight stressing the cables.

In an elevator filled with water...a person that might push against the bottom floor of the elevator to move up if not buoyant will add stress to the cables for that moment but since the person is suspended in that water the total stress upon the cables after the person becomes buoyant will be due to the total weight of the water the elevator and the person.

In the elevator with air...due to the inability of air to suspend a person...once the person jumps and after the force of their leap effects the elevator...the stress will be reduced while the person is in air and this is the TOTAL AMOUNT OF TIME after their leap adds stress as they go up...peak...and then go down.

They do not have to achieve weightlessness.

Split Infinity