# How to control the weight of an object?

• Nuno Miguel
In summary, Nuno Miguel is looking for a way to make an object with a certain mass have a lower weight, without using any external weight-reducing mechanics.
Nuno Miguel
Hello everyone,

First off, i would like to apologize for any spelling errors. I am Portuguese and my english is going to be very simple.
I am in the process of building something and i am reaching out to the physics community for help solving a problem.
I am a CNC programmer and while i was in one of my classes in school (Pneumatics) the teacher spoke to us about the principal behind a "Pneumatic Jack" and an "Air Check Valve".
Basically, the valve makes it possible for a human being to lift a car with just the strength of his arms.
This gave me an idea...and a problem to solve.
How do i control the weight of an object?

I need to be able to choose the weight that the object will have with just the turn of a button.
Think of a sphere...it has a button on the side, it's inicial weight is "2 pounds", but if i turn the button to "5", the weight is now "5 pounds".

I've been looking for maybe an element with expending mass, maybe the combination of two elements, where one affects the composition of the other, causing it's mass to expande, but i also need it to retract to it's original weight with another turn of the button to "2".
.
Maybe something in the fields of magnetic forces or electrical current?
I am neither a physicist nor a chemist so this is just me rambling.

This is a question a leave to you if you'll accept the challenge.
Again, sorry for my english, i hope i got the idea across.

Thank you for your attention, and i would really appreciate any feedback.
Take care.

Nuno Miguel said:
How do i control the weight of an object?
Hi and welcome to PF.
Basically you can't unless you take it to the Moon or somewhere else with a lower g field. You could do your experiment by pumping water in or out of a container and that would change the load on your jack. A "button" could control the pumping.

Or you could attach an elastic rope to the ceiling. Tighten the rope to reduce the weight and loosen the rope to return it to normal.

The usual way of providing a precisely variable force is with a "scale" or "balance".

You place an object whose weight is unknown on a spring scale and the device automatically applies just enough supporting force to keep that object motionless. One then examines the dial or digital readout to determine how much force was applied.

Or you place an object on the platform of a balance and add (or move) the right combination of weights to manually apply just enough supporting force to balance it exactly. One then counts the weights (or their offsets on an arm) to determine how much force was applied. [Or, more precisely, how much mass was balanced].

Nuno Miguel said:
I need to be able to choose the weight that the object will have with just the turn of a button.
Dale said:
Or you could attach an elastic rope to the ceiling. Tighten the rope to reduce the weight and loosen the rope to return it to normal.

https://encrypted-tbn0.gstatic.com/...a28fkDKEcdksM6bTgTNRZxZ9T0v0EkSCkIddMbwSAUKFg

#### Attachments

• images?q=tbn:ANd9GcRBVN_t1a28fkDKEcdksM6bTgTNRZxZ9T0v0EkSCkIddMbwSAUKFg.jpg
8.9 KB · Views: 821
Dale
As others have pointed out, there are ways of compensating for weight by
- providing some alternate lifting mechanism (buoyant gas, elastics, electromagnetism, etc.), or
- using mechanical advantage, such as a lever
- moving it to a lower gravity location.

But if you're looking to literally make object X have lower mass, you're out of luck.

Last edited:
Levers work fine.
A truck balance for example can weigh a truck of several tons, just by moving a small weight on a beam to different positions.

By changing the length of the lever arms, or the position of the fulcrum, you can change the "weight" of the mass at your desire.
Maybe use a rolling fulcrum.

( This didn't post at around 0830 EST so its late Internet jinx )

Nuno Miguel said:
This gave me an idea...and a problem to solve.
How do i control the weight of an object?
I'm going to spoil your party here, I'm afraid and ask you "What object and by how much do you want to vary it?"

sophiecentaur said:
I'm going to spoil your party here, I'm afraid and ask you "What object and by how much do you want to vary it?"
I'm more concerned that he's looking for a way to change the physical property of said object so that it actually masses less, not weighs less - and do so without the use of external weight-reducing mechanics, such as balloons or levers.

sophiecentaur
There has been no feedback from @Nuno Miguel yet. Without it, we are in a vacuum, I think.

davenn and berkeman
You could reduce its wait by vacuuming once a day instead of once every five years.

[Pun intended]

Last edited:
jbriggs444 said:
You could reduce its wait by vacuuming once a day instead of once every five years.
Funny typo making your statement a tautology...

lekh2003
berkeman said:
Funny typo making your statement a tautology...

haha

I didn't even pick that one up

davenn said:
haha
I didn't even pick that one up
I thought that was the pun. Which is why I thought berk's comment about it seemed redundant.

DaveC426913 said:
I thought that was the pun. Which is why I thought berk's comment about it seemed redundant.
Notice the timestamps on my reply and jbriggs editing his post. Sneaky...

davenn and jbriggs444
DaveC426913 said:
I thought that was the pun. Which is why I thought berk's comment about it seemed redundant.
as berkeman said, you saw it too late

jbriggs has already edited it after he saw berkeman's comment

berkeman
BTW, there's a good way to increase the weight of an object at will.

When the SWAT officer steps on the scale to get his weight recorded every 12 hours during a 48-hour exercise, you can observe one of his "partners" sneaking up behind him and adding his toe to the back of the scale. When done skillfully, this can cause said officer to worry that he will get booted from the exercise for excessive water weight gain or loss. LOL. Not that I've ever been part of a medical team watching this tomfoolery...

davenn
berkeman said:
you can observe one of his "partners" sneaking up behind him and adding his toe to the back of the scale.
Cue the classic Norman Rockwell picture.

berkeman
berkeman said:
LOL. Not that I've ever been part of a medical team watching this tomfoolery...
noooo, of course not, you would never be involved in anything like that

This thread has descended into lame puns.

If you really want to change the weight of an object simply add or remove mass. My water tank does this by pouring water in at the top, letting it out at the bottom.

## 1. How do I calculate the weight of an object?

To calculate the weight of an object, you will need to know its mass and the strength of the gravitational force acting on it. The formula for weight is W = m x g, where W is weight, m is mass, and g is the gravitational force. The unit of measurement for weight is typically Newtons (N).

## 2. Can I change the weight of an object?

Yes, the weight of an object can be changed by altering its mass or the gravitational force acting on it. For example, if you increase the mass of an object, its weight will also increase. Similarly, if you change the location of the object to a planet with a different gravitational force, its weight will also change.

## 3. How can I make an object lighter?

There are a few ways to make an object appear lighter. One way is to decrease its mass, which can be achieved by removing material from the object. Another way is to reduce the gravitational force acting on the object, which can be done by changing its location to a planet with a weaker gravitational force.

## 4. Is it possible to make an object weightless?

No, it is not possible to make an object completely weightless. All objects have mass and will be affected by the gravitational force to some degree. However, the feeling of weightlessness can be achieved temporarily in environments such as space or during free-fall.

## 5. How can I control the weight of an object in practical applications?

The weight of an object can be controlled in practical applications by using methods such as adjusting the object's mass, using lifting aids or machinery, or changing the gravitational force acting on the object. In some cases, it may also be possible to distribute the weight of an object evenly to make it easier to handle.

• Mechanics
Replies
1
Views
3K
• Science Fiction and Fantasy Media
Replies
6
Views
1K
• Mechanics
Replies
4
Views
3K
• Electromagnetism
Replies
28
Views
3K
• Sci-Fi Writing and World Building
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
7
Views
2K
• Electrical Engineering
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
2
Views
2K