How Do You Know if an Object Is More Dense

Objectives

• Demonstrate how the distribution of molecules in a substance determines its density.

• Investigate the relative densities of liquids and the relative densities of solids.

• Predict, test and explicate relative density by investigating the interactions of liquids and solids.

• Demonstrate understanding of the relationship between density and buoyancy past building a gunkhole.

Materials

• see individual activities for materials.

Background

Density, Mass & Volume

Simply put, density is how tightly "stuff" is packed into a defined space.

For example, a suitcase jam-packed with clothes and souvenirs has a high density, while the aforementioned suitcase containing two pairs of underwear has low density. Size-wise, both suitcases look the same, only their density depends on the relationship between their mass and volume.
Mass is the amount of matter in an object.
Volume is the amount of infinite that an object takes upward in three dimensions.

Density is calculated using the following equation: Density = mass/volume or D = g/v.

Let's compare three familiar substances to explore the concept of density. If we accept the same volume (1 cubic centimetre) of foam, wood and concrete, we can come across that each has a different mass.

Less Dense, More Dumbo

If something is heavy for its size, it has a loftier density. If an object is light for its size it has a depression density.

A pebble is heavy for its size, compared to a piece of popcorn which is light for it'southward size.  Imagine a big bowl of popcorn, compared to a big bowl of pebbles, which would feel heavier?

It is easy to gauge relative densities if you keep either the volume or the mass of two objects the same.

If you lot filled i pocketbook with a kg of feathers and another with a kg of pb y'all would see that the feathers take up much more than room, even though both numberless take the aforementioned mass. This because feathers are less dense, they have less mass per book. If you made a copper cube and an aluminum cube of the same volume and placed one in each mitt, yous would be able to experience that the copper cube would be heavier. Copper has more mass per volume than aluminum.

How can one substance have more mass per volume than some other? There are a few possibilities:

1. Atoms of one substance might be a similar size yet accept more mass than the atoms of another substance.
2. Atoms of one substance might exist a similar mass but be smaller, so more of them fit inside the same volume.
3. Atoms of 1 substance might be arranged in a way that allows more of them to fit in the aforementioned volume.

Whatsoever i or a combination of these explanations could be the reason why one substance has a college density than another. In the instance of copper and aluminum, their atoms are arranged similarly, just copper atoms are smaller and accept more mass than aluminum atoms, giving it a higher density.

Density, Sinking and Floating
Why do some things float, while others sink? You might expect heavier objects to sink and lighter ones to float, but sometimes the reverse is truthful. The relative densities of an object and the liquid it is placed in determine whether that object volition sink or float. An object that has a higher density than the liquid it's in volition sink. An object that has a lower density than the liquid it's in volition float.

You tin can really see relative densities at work when you look at a heavy object floating and a lighter i sinking. For example, imagine putting a minor piece of clay and a large, heavy wax candle in a tub of water. Even though it's lighter, the piece of dirt has a higher density than water and therefore sinks. Even though information technology's heavier, wax has a lower density than water, and so the big candle floats.

Sinking and floating applies to liquids as well. For example, if you add together vegetable oil to h2o, the oil floats on top of the water because the oil has a lower density than the h2o.

Buoyancy and Archimedes' Principle
The ancient Greek philosopher Archimedes found that when an object is submerged in water, information technology pushes aside (or displaces) an corporeality of water with the same mass every bit the object.

The water pushes upward against the object with a forcefulness (buoyancy) equal to the weight of water that is displaced.

Let's explore Archimedes' principle by dropping a bowling ball into a tub of h2o. When the ball is submerged in the water, it displaces its book in water. According to Archimedes' principle, the water tin "push back" with a forcefulness equal to the weight of the water that has been displaced.

A litre of water has a density of 1 kilogram per litre (i kg/L), and then a bowling ball's worth of h2o (four.5 50) can push back on the bowling ball with a force equal to 45 newtons (N). That's the weight of a iv.5 kg mass. Even so, the weight of the ball is more like 55 Northward. That's more than the buoyant force of the h2o information technology displaced, and so it sinks.

A beach ball may take the same volume every bit a bowling brawl, but information technology has a much smaller mass. When you a embankment brawl in a tub of water, it displaces the mass of water equal to its own mass—most 0.01 kg. If you were to attempt to push the beach ball downwards and readapt more than water, the h2o would push back with a strength greater than the weight of the embankment brawl. The push button of the water keeps the embankment brawl afloat.

Buoyancy is the upwards force nosotros need from the h2o to stay afloat. Buoyant forces are why we experience so much lighter when we are in a swimming pool. Our bodies are generally water, and so our density is fairly close to that of h2o. Considering of this, an average person needs simply a little bit extra buoyancy to float. A life jacket provides this extra lift.

Irresolute Density
You tin can alter the density of a substance by heating it, cooling it, or by calculation something to information technology. If an object sinks in h2o, it's because the object has a higher density than the water. There are ii possible ways to make that object float, however:

1. Increase the density of the water so that the water becomes denser than the object. For case, an egg will ordinarily sink in a drinking glass of water, considering it is denser than water. Adding common salt to the water increases the density of the water, allowing the egg to float. This experiment too works with people, but y'all need a lot of salt (endeavour the bounding main, or even better, the Dead Sea !)
   
2. Increase the book of the object and then that the object becomes less dense than the h2o. A great example of this is water ice floating in water. Ice is formed past freezing h2o. When it freezes, it increases in volume equally the h2o molecules move farther apart to suit the lattice construction of ice. Because the ice is at present less dense than water, information technology floats. This phenomenon too explains why ships float even though they are made of steel. A send is built in such a mode that information technology encloses big amounts of open space. The ship still displaces its weight in water, merely because of the fashion the ship is constructed, it takes upwardly more space than the volume of the h2o it displaces, so information technology floats.
   

Vocabulary

Archimedes: Greek mathematician, physicist, engineer, inventor and astronomer (c. 287 BC–c. 212 BC).
Archimedes' principle: Whatsoever object wholly or partially immersed in a fluid is buoyed by a forcefulness equal to the weight of the fluid that is displaced by the object. In other words, the buoyancy is equal to the weight of the displaced fluid.
buoyancy: The upward force that a fluid exerts on an object less dense than itself; the power to float.
density: How closely packed together the molecules of an object or substance are.
displace: To push out of the fashion. For example, when an object goes into water, it displaces the h2o.
immiscible: Unable to be mixed together, similar oil and water.
ironwood: The name for a large number of woods that have a reputation for hardness and high density.
mass: The amount of affair in a given infinite.
affair: The substance that makes up all physical things.
pumice stone: Lava barm known for its small mass and low density, despite looking similar a stone.
weight: A measure of the force of gravity on an object.
volume: The amount of infinite a substance or object takes up.

Other Resource

BrainPOP | Scientific discipline | Matter & Chemical science | Measuring Matter

EDinformatics | Mass, Volume, Density

WatchKnowLearn.org | Buoyancy and Density

ProTeacher Drove | Density

saulthimenfle.blogspot.com

Source: https://www.scienceworld.ca/resource/floaters-and-sinkers/

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