Weightlifting mathematically

[rino60]

Weight of an object = the force on the object
This is a fact
If the force required is less, the weight is less

Now I know why you have pissed off everyone of worth on this forum. Get off the Internet, and go to a few first year engineering / physics lectures.

Weight is defined as the force exerted on an object due to gravitational pull. Therefore, w =Fsub(g)=masub(g)=mG (G = g @ surface of 9.8067m/s^2)

 

[0ni]

so a 5kg stone that is thrown at the floor isnt 5kg when it hits the floor?

It's mass would stay the same.
If you throw a stone upwards in the air, force stops being applied to it (apart from gravity) so it would actually have negative weight - or weigh more depending on which way you look at it (fucking relativity)

 

[Bella]

lol Sticky mine too!!

But what callan said actually makes sense to me.


This is why when a stupid kid throws a rock from a bridge into oncoming traffic, it can kill the person it hits. Because you're spot on callan!


If you throw a 2kg rock, from height, with gravity + force, that rock will not be 2kg upon impact. The rocks weight hasn't changed, it's the force with which it's thrown + gravity or momentum that makes it heavier.


Because when the rock is recovered, unless it's damaged, it's still a 2kg rock.

Therefore 0ni is correct...Weight of an object = the force on the object

When two 90kg footballers collide on the field - it's not 180kg slamming into one another - it's 180kg + force + momentum + gravity if they happen to be on their way down at the moment of impact....(no wonder footy players get hurt!) farrkkk


Interdasting! lol

 

[0ni]

Now I know why you have pissed off everyone of worth on this forum. Get off the Internet, and go to a few first year engineering / physics lectures.

Weight is defined as the force exerted on an object due to gravitational pull. Therefore, w =Fsub(g)=masub(g)=mG (G = g @ surface of 9.8067m/s^2)

>your face when my degree is in engineering

What you're saying is correct but you fail to factor in that net force decreases as force increases against gravity

 

[callan]

It's mass would stay the same.
If you throw a stone upwards in the air, force stops being applied to it (apart from gravity) so it would actually have negative weight - or weigh more depending on which way you look at it (fucking relativity)

the weight is still the same, just the upward force is greater than the force of gravity. but the force of gravity still applies to the object so it is still the same weight.

 

[rino60]

because the force of the bands upwards against the bands is making the force of gravity less. And weight = mass * gravitational force

This is where you are wrong. You have actually finally stated that weight is a function of mass (constant) and gravitational acceleration (NOT FORCE). I get that you mean acceleration, and you agree that gravity is more or less constant. So the force of gravity does not decrease, and the weight does not decrease, but the NET downward force does, due to a positive (or upward) force.

 

[0ni]

the weight is still the same, just the upward force is greater than the force of gravity. but the force of gravity still applies to the object so it is still the same weight.

The net gravitational force is negative

 

[rino60]

>your face when my degree is in engineering

What you're saying is correct but you fail to factor in that net force decreases as force increases against gravity

No, I don't fail to factor that in, as you'll notice by my next post. If you do have a degree in engineering, then you would benefit from a few English classes, because you have FINALLY denoted that NET FORCE (downward) decreases. Weight (downward force due to gravity only) is constant.

 

[0ni]

This is where you are wrong. You have actually finally stated that weight is a function of mass (constant) and gravitational acceleration (NOT FORCE). I get that you mean acceleration, and you agree that gravity is more or less constant. So the force of gravity does not decrease, and the weight does not decrease, but the NET downward force does, due to a positive (or upward) force.

If that were true then g-forces would not exist

 

[Darkoz]

This thread hurts my head...... Cant we talk about squats or something?

Oni has a way of confusing and complicating things that aren't that complicated.
Going back to the original statement that started all this, he said that the weight of the bar DECREASES as speed increases.
Now we all know that this just doesn't happen, a 240kg bar will always be a 240kg bar no matter how fast you try and move it.

Then he went on a tangent about relativistic mass and other confabulating bullshit and confusion ensued.

 

[0ni]

No, I don't fail to factor that in, as you'll notice by my next post. If you do have a degree in engineering, then you would benefit from a few English classes, because you have FINALLY denoted that NET FORCE (downward) decreases. Weight (downward force due to gravity only) is constant.

I like how you try to insult me

 

[rino60]

The net gravitational force is negative

The net FORCE is negative. The gravitational force is constant. If you want to argue a subject that you actually finally appear to know something about, be very specific with your terminology. Because you're contradicting yourself in your terms.

 

[rino60]

I like how you try to insult me

I don't try and insult you, I am simply telling you that if you want to be accurate on a topic that requires such specification, you need to use the correct terminology.

 

[callan]

Oni has a way of confusing and complicating things that aren't that complicated.
Going back to the original statement that started all this, he said that the weight of the bar DECREASES as speed increases.
Now we all know that this just doesn't happen, a 240kg bar will always be a 240kg bar no matter how fast you try and move it.

Then he went on a tangent about relativistic mass and what not and confusion ensued.

lol oni so high

with all his talk of mass and net force and shit

 

[0ni]

The net FORCE is negative. The gravitational force is constant. If you want to argue a subject that you actually finally appear to know something about, be very specific with your terminology. Because you're contradicting yourself in your terms.

g-force - Wikipedia, the free encyclopedia

"The term g-force is technically incorrect as it is a measure of acceleration, not force. While acceleration is a vector quantity, g-forces are often expressed as a scalar, with positive g-forces pointing upward (indicating upward acceleration), and negative g-forces pointing downward. Thus, a g-force is a vector acceleration.

G-forces, when multiplied by a mass upon which they act, are associated with a certain type of mechanical force in the correct sense of the term force, and this force produces compressive stress and tensile stress. Such forces result in the operational sensation of weight, but the equation carries a sign change due to the definition of positive weight in the direction doward, so the direction of weight-force is opposite to the direction of g-force acceleration:
Weight = -mass x (g-force acceleration)"

"The experience of no g-force (zero-g), however it is produced, is synonymous with weightlessness."
Less g-force (net force with or against gravity) = less weight

 

[Darkoz]

It's mass would stay the same.
If you throw a stone upwards in the air, force stops being applied to it (apart from gravity) so it would actually have negative weight - or weigh more depending on which way you look at it (fucking relativity)

The stone doesn't weigh less because you threw it into the air FFS, it moved upwards because an opposite force was applied to it, it's mass AND weight would be the same.

 

[0ni]

The stone doesn't weigh less because you threw it into the air FFS, it moved upwards because an opposite force was applied to it, it's mass AND weight would be the same.

weight = force
you weigh nothing freefalling out of a plane, your mass is the same

 

[wingman]

Many a mathematical noob in this thread.

 

[rino60]

Good old Wikipedia. This is where I reference the wiki page for 'Weight' which will inevitably state something like 'weight is the product of mass and gravitational force'. Which you have agreed is constant for all considerations.

Ah well, I'm starting to realise that your conversation ain't worth staying awake for tonight. Hilarious some days, innane the next.

Anyone else want to roll with this? I'm going to sleep.

 

[Darkoz]

weight = force
you weigh nothing freefalling out of a plane, your mass is the same

What!?
Weight = the force of GRAVITY
Mass = the amount of matter an object contains

You freefall BECAUSE of the force of gravity acting on you therefore you have weight, if you weighed nothing then you wouldn't be falling in the first place.