A mass can be be lifted with force less than its weight

[studiot]

23 minutes ago, awaterpon said:

If I stand on scale surface the scale will read my weight 57 kg when I press the surface to pick a fruit from a tree I will push by small force 8 kg or less to raise my body*

While I lifting myself the scale will start reading small forces x in which the scale total read will read 57+x kg . I push the scale with small forces maximum 8 kg and the total force on the scale will be 57+8 kg or less when I stop upwards the scale will drop to 57 kg which is my actual  weight"no forces acting"

 

*These details are above.

Have you ever tried this ?

Would you like me to post some photographs of what happens when I stand on my domestic bathroom scales and press up to stand on tiptoe ?

The reading is rapidly disturbed by many kilogrammes. Downwards (towards much lower reading)

Then the scale spins more slowly back to the same reading it was before I moved.

 

This effect does not noticeably happen on a commercial weighing machine for sacks of sand, flour or whatever or on a weighbridge.

 

This is because the flimsy domestic machine is based on a cantilever which substantially changes deflection further when you redistribute the load, before some compensation mechanism (if any) kicks in.
This is why the manufacturer's instructions say to stand quietly and squarely in the middle on both feet with both flat to obtain a correct reading.

[awaterpon]

1 minute ago, studiot said:

Have you ever tried this ?

No, I don't have a scale with surface I only measure my weight in my doctor clinic.

 

8 minutes ago, studiot said:

Would you like me to post some photographs of what happens when I stand on my domestic bathroom scales and press up to stand on tiptoe ?

 

This will be great I would love to

 

[Bufofrog]

17 hours ago, awaterpon said:

So if my maximum force of calves muscles I can exert is 8 kg then the maximum force I can exert to lift my body as I described is only 8 kg .

So you are saying a 8kg force (80N) can lift a 60 kg mass.  Absurd.

This is based on your incorrect belief that you can only produce 80N of force when you raise your heels off the ground so your weight is on the balls of your feet.  You have been making this silly claim for a while.  Why don't you just go to the gym and use the calf press equipment to see how much your calves can actually lift?

[swansont]

1 hour ago, awaterpon said:

If I stand on scale surface the scale will read my weight 57 kg when I press the surface to pick a fruit from a tree I will push by small force 8 kg or less to raise my body*

While I lifting myself the scale will start reading small forces x in which the scale total read will read 57+x kg . I push the scale with small forces maximum 8 kg and the total force on the scale will be 57+8 kg or less when I stop upwards the scale will drop to 57 kg which is my actual  weight"no forces acting"

*These details are above.

So this means you are exerting an additional ~80 N of force (+8 kg display) in order to raise your body. 

This number will vary, depending on how fast you do this. Doing it faster requires a larger acceleration, which requires a larger force. You would see this if you jumped.

57 kg (~570 N) is not the weight with no forces acting. Gravity as acting on you, as is the normal force of the scale on you, and you are exerting a normal force on the scale. 

i.e. that's what you are exerting on the scale with no additional effort. There is no point in this example where you can say no forces are acting on you.

 

 

 

[studiot]

1 hour ago, awaterpon said:

No, I don't have a scale with surface I only measure my weight in my doctor clinic.

Well I am disputing that you can actually press down on your scales with a force greater than your own weight, without pushing against another (relatively immovable) object.

So try it next time you visit a clinic or ask a neighbour.

 

When you jump or rise slowly you are configuring your body as a see-saw or medieval catapault so that you can get necessary leverage to multiply the force on one side of the fulcrum.

Note again that the reading on my bathroom scale drops when I stand on tiptoe.

The value of this drop depends how fast or gently I stand up.

So if I stand gently on the scale and wait till the dial settles at 70kg, then stand up very quickly it drops very rapidly to about 18 kg then returns to 70kg.

The faster I stand the greater the drop.

If I stand very slowly and gently the scale barely flickers below 70kg.

At no time does it exceed 70kg.   -   the static value.

 

1 hour ago, awaterpon said:

This will be great I would love to

It really needs a video, I will try to obtain one and get help to post it here.

I don't think still photography will work here.

But you really should conduct the experiment for yourself and see what happens.

[awaterpon]

On 3/19/2021 at 4:13 PM, studiot said:

When you jump or rise slowly you are configuring your body as a see-saw or medieval catapault so that you can get necessary leverage to multiply the force on one side of the fulcrum.

Physically the force  to lift a mass must always be greater than the mass weight  , a lever convert a force into force that is greater than mass weight so the other side of any lever must have force greater than weight regardless  what the force I exert is

When I stand on  the scale my foot will be a lever, its fulcrum is at my foot toes and both the alternative weight and force to lift my alternative  mass are on the heel " lever class 3" so I will need force slightly greater than my alternative weight, my alternative weight can be determined when I stand on the scale and lift myself with a specific acceleration not too slow not to fast " just slightly greater than my alternative weight"the scale then will read my alternative weight F where 570+F is what is displayed in the scale screen.

Edited March 22, 2021 by awaterpon

[Ghideon]

2 hours ago, awaterpon said:

alternative weight and force to lift my alternative  mass

I would like to see a rigorous definition of "alternative weight" "alternative mass". 

 

[swansont]

4 hours ago, awaterpon said:

Physically the force  to lift a mass must always be greater than the mass weight  

So you agree that your claim "My hypothesis  is that a human body can lift itself  by a force far less than its weight" is wrong?

 

 

[studiot]

Thomas, this is on a par one experience in my life where a chartered engineer with degrees and theoretical calculations' and such stood next to me observering a test pile being pushed ito the London Clay with a force lower than his theoretical calculations required  -  and would not believe it.

I posted a list of readings from my scale.

You did not respond.

Have you repeated the experiment for yourself ?

[swansont]

54 minutes ago, studiot said:

Thomas, this is on a par one experience in my life where a chartered engineer with degrees and theoretical calculations' and such stood next to me observering a test pile being pushed ito the London Clay with a force lower than his theoretical calculations required  -  and would not believe it.

I posted a list of readings from my scale.

You did not respond.

Have you repeated the experiment for yourself ?

You talking to me?

 

yes, I have done this. When I raise myself up on my toes, the reading on my scale increases above my weight by a few pounds. If I am settling back down, it decreases below my weight. That's consistent with a physics analysis. In order to have a +y acceleration, there must be a force greater than the weight acting on the person. Consequently, the person must be exerting a force greater than the weight on the scale. AFAIK my scale is basically a spring scale - just a pad with some internal components. 

I can only conclude that your scale has some interesting goings-on for your reading to go down, but then, we also know a pendulum doesn't work properly when accelerating, so a cantilever might be similarly perturbed. It might be fun to analyze why this happens.

The concept is like the scale reading on an elevator

https://lhsblogs.typepad.com/files/apparent-weight.pdf 

[studiot]

1 hour ago, swansont said:

You talking to me?

No but thank you for your response.

I had not given any thought to your initial, Thomas was a biblical reference.

No offence meant to anyone.

 

I tried it on both an older mechanical scale and a more modern electronic one.
The effect happens on both but is more pronounced on the mechanical one.

It must be remembered that a bathroom scale has a large distribution platform supported on a post of very small cross section which is no doubt why the manufacturers instruct the user to stand squarely and quietly on the platform.

[awaterpon]

 

On 3/22/2021 at 11:23 AM, Ghideon said:

I would like to see a rigorous definition of "alternative weight" "alternative mass". 

 

The alternative weight is the force by gravity on a human which opposes human lifting himself

Alternative mass is the mass with  inertia that opposes body moving himself

 

On 3/22/2021 at 2:07 PM, studiot said:

You did not respond.

Have you repeated the experiment for yourself ?

Unfortunately I live in a poor country ,these scales are rear only in clinics and hospitals ,and in the market it is too expensive for me to buy

Edited March 23, 2021 by awaterpon

[Bufofrog]

56 minutes ago, awaterpon said:

The alternative weight is the force by gravity on a human which opposes human lifting himself

No, that is normal weight.

58 minutes ago, awaterpon said:

Alternative mass is the mass with  inertia that opposes body moving himself

No, that also is normal weight.

59 minutes ago, awaterpon said:

Unfortunately I live in a poor country ,these scales are rear only in clinics and hospitals ,and in the market it is too expensive for me to buy

Sorry to hear that.

[awaterpon]

1 hour ago, Bufofrog said:

Sorry to hear that.

Why not you use your scale and try it yourself?

[Ghideon]

3 hours ago, awaterpon said:

The alternative weight is the force by gravity on a human which opposes human lifting himself

Alternative mass is the mass with  inertia that opposes body moving himself

 

Let's try something else. What objects can replace the word "human" in your definition and still give exactly the same results as you claim? Can "human" be replaced by "dog", "humanoid robot" or something else?  

Edited March 23, 2021 by Ghideon
grammar

[awaterpon]

6 minutes ago, Ghideon said:

Let's try something else. What objects can replace the word "human" in your definition and still give exactly the same results as you claim? Can "human" be replaced by "dog", "humanoid robot" or something else?  

Flesh.Perhaps bones as well

[Ghideon]

4 minutes ago, awaterpon said:

Flesh.Perhaps bones as well

What are the properties of flesh (and bones), according to your idea, that makes the difference?

[Bufofrog]

3 hours ago, awaterpon said:

Why not you use your scale and try it yourself?

I already know the answer, I don't need to prove to myself that rest mass is rest mass.  

[J.C.MacSwell]

On 3/22/2021 at 10:01 AM, swansont said:

You talking to me?

 

yes, I have done this. When I raise myself up on my toes, the reading on my scale increases above my weight by a few pounds. If I am settling back down, it decreases below my weight. That's consistent with a physics analysis. In order to have a +y acceleration, there must be a force greater than the weight acting on the person. Consequently, the person must be exerting a force greater than the weight on the scale. AFAIK my scale is basically a spring scale - just a pad with some internal components. 

I can only conclude that your scale has some interesting goings-on for your reading to go down, but then, we also know a pendulum doesn't work properly when accelerating, so a cantilever might be similarly perturbed. It might be fun to analyze why this happens.

The concept is like the scale reading on an elevator

https://lhsblogs.typepad.com/files/apparent-weight.pdf 

+1

During the time you spend on a scale, getting on, stepping off, outside forces notwithstanding, the force you put downward on the scale has to average over time at your weight...whether the scale accurately reflects that depends on the intricacies of the scale. Movement on the scale may temporarily change the downward force, either up or down, but if you start and finish at rest in the same spot it will average to be your weight.

(not exactly exactly...as you can vary your buoyant force by compressing air in your lungs, etc, but heroics aside, mass loss from evaporation....anything I missed?...)

 

Change in pull of the sun or moon?

There are more but nothing significant. The scale will on average see a downward force equal to your weight, and whether it reflects it or not depends on the scale, not the downward force it opposes.

As to: "A mass can be be lifted (raised to a higher level) with force less than its weight", if it has upward momentum you can maintain some of that for longer with a lesser force than it's weight than with none at all, and get it to a higher level than it would have otherwise...so yes?

[swansont]

8 hours ago, J.C.MacSwell said:

Change in pull of the sun or moon?

I like to point out that the effect of the moon's pull on pendulum clocks has been measured. Small effect, of course, but it's there.

[J.C.MacSwell]

6 minutes ago, swansont said:

I like to point out that the effect of the moon's pull on pendulum clocks has been measured. Small effect, of course, but it's there.

Sun also?

[swansont]

52 minutes ago, J.C.MacSwell said:

Sun also?

I'd have to think about this. The acceleration is there, but we are also in freefal. about the sun owing to our orbit. (Need caffeine to make brain work)

 

edit:

A confounding factor is the change in the mass distribution of the earth owing to the tides. g gets bigger or smaller because of the moon or sun, but the water moves around if you're near the coast, and all that water moving depresses the crust a small amount. The net effect is the body being overhead reduces g, but the nearby mass increases it, reducing the net effect 

As it's a tidal effect, the impact of the sun is smaller. As you would be getting closer to the limit of the pendulum clock's stability, the difficulty in measurement is bigger than the simple difference in the magnitude of the effect; the net variation is (IIRC) a few milliseconds per day, and the limit of the best pendulum clocks are a little under a millisecond, so the sun's effect is closer to being lost in the noise (S/N of 5 is markedly easier to measure than a S/N of less than 2)

 

[studiot]

Ok I have enlisted the aid of a small person with a mobile phone and obtained a short video of what happens on my bathroom scale.

It is 6.2MB and a couple of seconds long, in MP4 format.

So I am seeking some help posting it her for all to see as I have never posted a video here before.

Edited March 24, 2021 by studiot

[awaterpon]

23 hours ago, studiot said:

Ok I have enlisted the aid of a small person with a mobile phone and obtained a short video of what happens on my bathroom scale.

It is 6.2MB and a couple of seconds long, in MP4 format.

So I am seeking some help posting it her for all to see as I have never posted a video here before.

You will need to upload it in a site like YouTube copy the video URL insert it by one of the upper icons ,you also can give it a title in the text blank.

[Prof Reza Sanaye]

The defined  circulatory relations amongst mass , force , and acceleration (by Newton) makes it virtually impossible to have any spatiotemporal motion/acceleration  set in locally meaningful topological manifold(s). 

Another confounding parameter is the fact that weight , much more closely hermeneutically interpreted to be force , rather than mass or acceleration , is itself partially recognized by pre-Newtonian systems ( Galilean , Keplerian ) to have nothing in common with incremental propagation of gravitation (force) as waves or something in space. They did not recognize any fixed-point acceleration dealing with propagation of gravity waves. Newton came in half-way and abstracted the facticity of his own system based on a kind of teleological causality.  Einstein claimed that he could not discard with causality , as QT does ,  , , , ,, , ,However , the change of gravity from a Force Status in Newtonian thinking to one of Spacetime differentials of geodesicity in Einsteinian thinking simply resolved fixed-point acceleration. The result is that we are now perplexed as to the quintessence of what leverage a force ought to overcome in order to do a locally defined coordinance of even relative-point motion. 

As an almost direct result , intelligent people like awaterpon come to fall in doubt as about the feasibility of : 

 

 

According to classical mechanics for a force to  lift a mass it should be slightly greater than its weight .

My hypothesis  is that a human body can lift itself  by a force far less than its weight .

It is obvious phenomenon that when lifting an object  of 60 kg up , it would be extremely hard than lifting one's body " 60 kg" .while standing.

This applied to many phenomenon  .A body will seem to have inertia far less than its actual mass inertia , moving and walking effortlessly , standing effortlessly , lifting one's body parts easily.

In this special case the Newtonian equations doesn't apply , however we could measure the ratio between the force lifting a body and the force lifting an object both body and the object have the same mass.