# Tagged Questions

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### Weight of empty versus inflated balloon [duplicate]

Will the weight of a balloon filled with air be less than, greater than or the same as the same balloon after it has been deflated?
7k views

### Doesn't a box holding a vacuum weigh the same as a box full of air?

This was recently brought up, and I haven't been able to conclude a solid answer. Let's say we have two identical boxes (A and ...
1k views

### Does the weight of an hourglass change when sands are falling inside?

An hourglass H weighs h. When it's placed on a scale with all the sand rested in the lower portion, the scale reads weight x where x = h. Now, if you turn the hourglass upside down to let the sand ...
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### Is a block of cotton heavier than a block of iron?

if i have a block of cotton and a block of iron each containing a weight of 100 kg when measured on a weighing machine, in reality which one is heaver than the other, which one is heavier and why? ...
3k views

### Floating Objects and Weight

The Situation: A ball is placed in a beaker filled with water and floats. It is also attached to the bottom of the beaker via a string. The Question: The ball is attached to the beaker, thus ...
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### Possible solutions to the crown problem of Archimedes [closed]

My teacher was talking about the crown problem, possibly solved by Archimedes using skills about density, weight and other properties that he studied. In the original publication, by Vitruvius in a ...
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### How would filling a milk canister with helium affect the reading it makes on a scale?

Let's say that if I put a milk canister on a scale it shows 10kg. If I fill it with Helium it must necessarily be less than this, right? Can someone explain this (probably trivial) thing to me? :) ...
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### Vacuum to hold an object

How can i check and calculate if a certain vacuum pump can hold an object that weights X kg? By "hold" I mean not let that object fall to the floor due to gravity
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### Where on Earth does the mass of 1 kg actually produce a 1 kg reading on a digital scale?

Gravity on Earth varies by about 0.1% between poles and equator. If someone was buying/selling something mass critical e.g. gold, where is the standard place on Earth where a 1 kg mass produces a 1 kg ...
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### Why do we use kilograms instead of newtons to measure weight in everyday life?

What was the reason to use kilograms to measure weight (e.g. body weight, market vegetables etc.) instead of using newtons?
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### What is the weight of the Philae lander on the Churyumovâ€“Gerasimenko comet compared to earth?

We know the payload mass of the Philae lander was 21kg. We know the mass of the Churyumovâ€“Gerasimenko comet is roughly 1 x 10^13kg. We know the mass of Earth is roughly 5.9x10^24kg. I've heard ...
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### Effect of Earth's rotation on apparent weight (acceleration due to gravity) [duplicate]

What would be reason for change in weight due to rotation of Earth? How can the direction of $g'$ (The value of $g$ at any point on Earth) be the apparent vertical direction? Why isn't $g$ the ...
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### How the apparent weight varies due to the rotational motion of Earth?

I learned that as the earth rotates about its axis, the bodies on the earth also follow a circular path. In most books I read, they give the example of a person standing on a weight balance at the ...
4k views

### Why does cold water weigh more than hot water in a fixed volume?

Take a bucket of hot water and the other bucket of cold water. Why does the bucket full of cold water weigh more than bucket full of hot water?
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### When referring to weights and mass of weights in a physics laboratory, do we use the term mass or weights?

What terminology is used to refer to weights/ mass/ weight of mass/ mass of weights when referring to the mass of weights in a physics report? My question is more of the weights that we use in the ...
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### Weight of a material

I'm dealing with a problem here. Does a material lose weight when it transforms from solid to liquid? I believe it does. It loses weight because some of it becomes gas. Can anyone help me? Thank ...
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### Generating forces precisely [closed]

When we like to produce known forces, we know that standard weights acting vertically on a object creates a known force. Now, what are the other methods to generate forces with accuracy? It is a 'do ...
85 views

### Why does the air pressure at the surface of the earth exactly equal the weight of the entire air column above it

Why does the air pressure at the surface of the earth (resulting from collisions of molecules on the surface of the earth which has to do with the velocity of the particles) exactly equal the weight ...
131 views

### Weight versus gravitational force [duplicate]

What is the difference between weight and gravitational force? I am a beginner who want to study physics properly.
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### Can mass be directly measured without measuring its weight?

From Wikipedia, http://en.wikipedia.org/wiki/Mass Inertial mass measures an object's resistance to being accelerated by a force (represented by the relationship F=ma). Active gravitational ...
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### It seems wrong to find the mass using weight alone when using chemical compounds [duplicate]

The difference between mass and weight is pretty straightforward so then how can we WEIGH a substance then ask how many Daltons (atomic MASS units) are in that substance without a conversion in there ...
2k views

### Trouble understanding the concept of true and apparent weight

I need help understanding the concept of true weight vs apparent weight. I understand this much: if someone is standing in an elevator on a scale, the further up they go the less the reading on the ...
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### If earth generates magnetic field does it attract metal? [duplicate]

If earth generates magnetic field does it attract metal objects at the surface of the planet and make them heavier?
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### Do different density objects in liquids affect net weight [duplicate]

I would test this but I have no tools to test it with. If I have a beaker of water and weigh it on a measure. Then I stick my fingers in the water (it doesn't over flow) does the weight change or ...
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### How much work will a human do to lift a weight?

I saw a pretty simple homework question here that asked how much work it takes to lift a 200 kg weight, and while the math for a basic answer is simple the weightlifter in me instead wanted to ...
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### Do we weigh less in the morning? [duplicate]

A question on Biology SE got me thinking, ignoring weight naturally lost during the night, "Do we weigh less in the morning?" During the night, the sun is above us, and the earth below us. ...
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### How to weigh your nephew [closed]

My nephew is 3 and weighs around 30 pounds I am guessing. However, I would like to weigh him at home. I have kitchen scales, one flat one that goes up 1kg and one that looks like this picture that ...
683 views

### An atomic bomb explodes inside of an “unbreakable” container which is on a scale. Does the “weight” of the container change?

This may or may not be an incredibly stupid thought experiment, but a short time ago I read that most of the "mass" in the proton was actually energy from the quarks and gluons, as opposed to the ...
155 views

### When you breath in a helium balloon, do you lose weight?

We all know the trick of breathing in a helium balloon to get a funny squeaky voice! When you do this, would it be correct to say you lose weight? On the one hand, the helium should make you more ...
147 views

### Does the weight of an magnet raise when balancing an object?

I was wondering if say I use an magnet which is facing positive and then I expel an another magnet above it which is facing the positive with its positive side and I ensure the magnet does not rotate ...
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### Difference between weight of water and pressure of water

(I didn't even have a basic formal education in physics. I'm learning through the internet out of my own interest, so if there are any silly mistakes, kindly bear with and guide me through.) ...
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### How does a vertical counter-weight system work?

How does a vertical counter-weight system work when you have variable weight on one side? From what I understand from this page elevators use a counter weight to counter-balance the cart and some ...
688 views

### Does the weight of fluid in a conical container act entirely on the base?

Scenario description Lets assume both containers have a capacity of 300 litres. One is a vertical tube as shown in pic 1 Other one is more or less a V shaped containers as shown in pic 2 Both are ...
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### Apparent weight on a hill and in a ditch [closed]

first time posting. I'm trying to solve these 2 problems. I have a solutions I just don't know if I'm right...seems odd that they are the same answer... 1) If you are driving over a hill of ...
245 views

### Why is this mass equation giving me mass = weight when clearly it isn't?

Convert the weight measured in pounds to the equivalent in Newtons. In the formula for determining mass based on weight, mass is measured in Newtons. Weight is measured in Kilograms, and the ...
1k views

### Calculating electric motor's weight lifting ability knowing power. What else do i need to know?

So, my company works with electric motors, and my boss wanted me to calculate how much weight could be lifted by a motor rated at 750W. I know that i can't just calculate the work done by it without ...
29 views

### Audio anomaly identification

I left an audio recorder in the forest in many different locations for fauna identification. I am collecting subjects on my audio recorder that are clearly not in the frequency range of any animal ...
658 views

### How does mass relate to resistance (Ohm's Law)

How can I relate $mg$ to $R$? Just to give you a scenario: If a free hanging weight was tied to a motor... I know the voltage ($V$) and current ($I$) so I can use $V = IR$ to find $R$. What if I ...
59 views

### Exception to weight of hot vs cold water?

I have seen the various posts regarding the comparison of weight of heated and cold water.But is there any contradiction?I live in really hot conditions and as such tap water literally 'boils' ...
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I came up with this problem by myself: How much force do I need to make a pendulum revolve? Now I imagined that the force $\vec{F}$ must be enough to make the pendulum swing until half of the ...
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### Estimating the weight of a vehicle moving in a highway [closed]

I need to know the estimated weight of a truck in a highway without using scales. What do I have? Speed of the car at time X RPM at time X horse power Estimated distance from a point A to B ...
495 views

### What limitations are there in measuring physical properties accurately?

In a StackOverflow answer, I attempted to explain why a 32-bit float was perfectly adequate for representing the questioner's weight measurement: Physical properties are inaccurately measured ...
76 views

Say, in the example below, the weight $mg$ of the object is $800N$. To find $R$, the conventional method is to use $R\sin(28^\circ) = 800$. But why isn't it possible to use instead the component of ...
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### Perceived weight in dumbbell vs. barbell

I had an observation today at the gym when I was lifting weights. Lifting a dumbbell of 10 kg on each hand was as difficult for me as lifting a barbell with 5 kg on either end. It's true that the bar ...
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### How long does an object experience motionlessness at the beginning of its descent?

When a rubber ball bounces, it first accelerates in the positive direction (downward) then it bounces (hits the floor) .The velocity then becomes negative as the ball declerates while travelling ...
4k views

### When we do pull-ups , does the bar takes more weight than when we hang down on the bar?

When I do pull-ups, I feel I push down to the bar. But does the bar really take more weight than just hang down? For people who don't know pull-ups and hang down, here is an illustration. Left: Hang ...
312 views

### Does object sealed in a airless place weigh more?

In a case where you vacuum your items in those airless bags(Space bags), do they weigh more ? Or is it just a feeling because of increase in density due to decrease in volume ?
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### Why does the heaviest point on a spinning ball tend to become the topmost pole? [duplicate]

I have a mostly hollow, small clear plastic ball. Inside the ball is a weight stuck to the edge but the weight is smaller than the ball so the ball will always come to rest with the weight at the ...