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awaterpon

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

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Posted (edited)

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.

Edited by awaterpon

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For one thing, a body is made of parts.

If you lift a 60 kg weight with your arm, the arm has to cope will all 60 kg.

A 60 kg person lifting themselves, does it in parts. Their neck lifts their head. Their core lifts their torso plus neck plus head. Their legs lift all the above.

It's not an apples to apples comparison. A 60 kg person doing a one-handed pull up or press up, would be a fairer comparison.

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46 minutes ago, pzkpfw said:

For one thing, a body is made of parts.

If you lift a 60 kg weight with your arm, the arm has to cope will all 60 kg.

A 60 kg person lifting themselves, does it in parts. Their neck lifts their head. Their core lifts their torso plus neck plus head. Their legs lift all the above.

It's not an apples to apples comparison. A 60 kg person doing a one-handed pull up or press up, would be a fairer comparison.

Thanks.

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Also, the total force on the ground will be exactly equal to the weight. And the force of the ground on the person will also be equal to that. So Newton is redeemed once again.

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45 minutes ago, Strange said:

Also, the total force on the ground will be exactly equal to the weight. And the force of the ground on the person will also be equal to that. So Newton is redeemed once again.

Thanks

It's unbelievable that I carry up my 60 kg body with only my feet when trying to pick  a fruit on  a tree.

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29 minutes ago, awaterpon said:

It's unbelievable that I carry up my 60 kg body with only my feet when trying to pick  a fruit on  a tree.

I find it quite believable and quite unremarkable.

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13 minutes ago, Bufofrog said:

I find it quite believable and quite unremarkable.

Thanks you.

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7 hours ago, awaterpon said:

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.

In the low speed situations you describe Newton always applies.

If course it depends exactly what you mean

Mechanical Advantage = Load / Effort

and an ME of greater than 1 is certainly achievable with suitable arrangements.

Of course you need to go a long way further back than Newton for some of these, right back to the ancient Greeks.

"Give me a long enough lever and a fulcrum and I will lift the world."

 

https://en.wikipedia.org/wiki/Mechanical_advantage

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6 hours ago, awaterpon said:

 

It's unbelievable that I carry up my 60 kg body with only my feet when trying to pick  a fruit on  a tree.

Why do you find this unbelievable, when you have grown up with this perfectly normal experience?

It is like saying "It's unbelievable that I can breath the air around me" or "It's unbelievable that I can hear the range of sounds that my ears are specifically made to receive" or "It's unbelievable that water is wet" or any number of perfectly ordinary things.

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Posted (edited)

Lol considering I am only  5 foot seven and 155 lbs my legs can press 250 kg for ten reps on a Universal machine. 60 kg is nothing.

Edited by Mordred

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54 minutes ago, Mordred said:

Lol

Indeed +1

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