[Kryptid]

I can lift my 60 kg body with only my weak feet muscles when trying to pick a fruit on a tree.

You must have forgotten about the significant muscle mass in your legs.

The muscles force  actually is far less than 588 Newton but it  lift the body .

What was it about, "the distribution of mass and the muscle groups employed are different in that scenario than they are for when you stand up from a sitting position" that you didn't understand?

[Yahya A.Sharif (OP)]

A thing could be noticed is the inertia of one's body seems far less than actual body mass inertia so walking is easy  , in fact all movements of a body are effortless moving any part of the body is easy compared to the body actual mass a person feels like his body is lighter than the actual mass of the body.
Is it possible for person to carry 70 kg rock and run ? I don't think an an average person who is not bodybuilding will even be able to lift a 70 kg weight .So how we even carry our bodies?

[Kryptid]

A thing could be noticed is the inertia of one's body  seems far less than actual body mass inertia, so walking is easy  , in fact all movements of a body are effortless , moving any part of the body is easy compared to the body mass, a person feels like his body is lighter than mass of the body.

What something "seems" like or "feels" like is not the same as what it actually is. Our muscles are collectively more than strong enough to move our bodies. An average man can leg press more than his own weight. That doesn't even take into consideration the other muscles, like those in your core and back, that help with standing up.

Is it possible for person to carry 70 kg rock and run ? I don't think an an average person who is not bodybuilding will even be able to lift a 70 kg weight .So how we even carry our bodies?

Are you serious? Your body has weight. If you are not carrying the rock, you are only carrying your own body's weight. When you carry a rock, you are carrying both your body's weight and the weight of the rock. Carrying a rock is obviously harder because the total weight being carried is higher. That should be obvious.

[Yahya A.Sharif (OP)]

An average man can leg press more than his own weight. That doesn't even take into consideration the other muscles, like those in your core and back, that help with standing up.

I'm not talking about legs I'm talking about feet which is used to carry up a person as I mentioned.The force to lift the person should be 588 Newton do you think the feet will provide such force when presses .?

[Kryptid]

I'm talking about feet which is used to carry up a person

The muscles in your feet do not lift you own their own. Your leg muscles are involved.

The force which should   lift a person by his feet is 588 Newton

Your calculation for that wasn't even sensible. People don't stand up by using their feet like that.

[Yahya A.Sharif (OP)]

The muscles in your feet do not lift you own their own. Your leg muscles are involved.

Right , the force involves my legs force , but do you think the force of feet and legs pressing equal 588 Newton ? or even close to it? you can just press your feet and find out how weak it is .

Your calculation for that wasn't even sensible. People don't stand up by using their feet like that.

I presented specific example , which turned out to be very sensible.

[Kryptid]

Right , the force involves my legs force , but do you think the force of feet and legs pressing equal 588 Newton ? or even close to it? you can just press your feet and find out how weak it is .

It doesn't need to because getting out of a chair isn't akin to the scenario you calculated.

I presented specific example , which turned out to be very sensible.

No it wasn't. You stated in your calculation that you put the fulcrum at the feet. If I'm sitting in a chair and trying to get into a standing position, the fulcrum would be at the knee instead. Or at least one of the fulcrums would be. Standing up uses many joints and many points of force application. A calculation assuming a simple lever breaks down because of that. You would need to calculate the forces acting along all of the relevant points of the body.

[Yahya A.Sharif (OP)]

It doesn't need to because getting out of a chair isn't akin to the scenario you calculated.
If I'm sitting in a chair and trying to get into a standing position, the fulcrum would be at the knee instead. Or at least one of the fulcrums would be. Standing up uses many joints and many points of force application. A calculation assuming a simple lever breaks down because of that. You would need to calculate the forces acting along all of the relevant points of the body.

Actually , the example doesn't involve body sitting or standing. Reply #16

[Origin]

The OP asked:
Can a mass be lifted with force less than its weight?

The obvious answer is:
Of course not.  It is embarrassing that someone would even ask the question.

He cannot be convinced he is wrong, he has shown that he Is impervious to logic.

[Bored chemist]

It seems to me that he hasn't understood the issues.
 Yahya A.Sharif
I can use a brick and a plank of wood as a fulcrum and a lever.
With those I can lift your weight very easily.



But the force at the "short" end of the lever- where it lifts your weight is still equal to your weight. (and eh force on trh brick is a bit more than your weight.

That's elementary physics.

You seem to think it is some sort of "magic".
It's not.

If you use your "feet" to lift yourself (actually, you use your calf muscles)
https://en.wikipedia.org/wiki/Calf_(leg)
 then the fulcrum is your toes. The load is your weight pressing down on your ankles and the force is applied from the calf muscles, via the achilles tendon.
https://en.wikipedia.org/wiki/Achilles_tendon

The load in that tendon is several times MORE than your weight.
Your calf muscles can each supply a force of several times your body weight.

They are remarkably strong, but it still isn't a breach of physics.

[Kryptid]

Actually , the example doesn't involve body sitting or standing. Reply #16

Oh, I see now. 30 centimeters seems an unreasonable distance for the lever of your foot. Even if your foot was that long, you don't stand on your actual toes when you stretch upwards. You are standing on the ball of your foot instead. Also, your center of gravity wouldn't be right at your heel. It should be closer to the center of your foot for the sake of balance.

[yor_on]

I don't think so?
The inertia needs to be overcome, even if the weight differ from the Moon to the Earth.

[Petrochemicals]

Yes weight can be lifted with a force less than it, through mechanical advantage, it is however possible to put less energy in than an object would gain.

https://en.m.wikipedia.org/wiki/Torque

[yor_on]

Yes, that's true PC, but the energy spent by lifting it should be the same as if was someone stronger f.ex, using a winch as in pulleys. If there was a way to spend less energy I would be very surprised. To me it seems as if you have a mass you will find a inertia, the inertia won't change even though the weight might. That's how I see it.

[Yahya A.Sharif (OP)]

These are other examples of a person lift or move himself with a smaller force:
A human can jump high raising his 60 kg weight while he barely moves a rock of 60 kg
A human can run fast with his massive 60 kg weight while he barely moves the same rock of 60 kg
An average person can lift his body of 60 kg holding a bar many times but he will barely move a rock of 60 kg

will a person climbing a ladder and falling on a generator turbine generate energy from nothing?
The input biological body energy exerted will be equal to the output energy represented by the body weight on the turbine and that  regardless of the calculations of muscles force and body weight .So energy is conserved

[Bored chemist]

will a person climbing a ladder and falling on a generator turbine generate energy from nothing?

No.
They will generate energy from food (which got it from sunlight).
But nobody said  this wasn't the case, so why did you ask the question?

Quite a lot of the energy in the food is "wasted" as heat, but that's another matter.
Overall, energy is conserved.

[Origin]

Why do our bodies  break fundamental laws of physics that is the laws regarding this thread?

They don't, this has been pointed out to you many times in this thread.

Does that mean the body have its own physics that governed by different laws and explains different phenomena of the body and  theses laws connected to each other in a way that the body has its own physics?

Of course not, don't be silly