Density and Upthrust

Density and Upthrust

         Density and Upthrust are very important concepts in physics, it's usage helps in a lot of scientific researches and also in solving real life problems, yet they are two distinctive concepts( Density and Upthrust ). Students have a misconception of these two things, but with the help of this post any smoke of misunderstanding will be blow and sucked away into oblivion. 

    In this topic today, we will look at the following:

❶ A better understanding of Density

❷ Density of common materials and substances

❸ Relative Density

❹ How to determine or find the density of a material or substance

❺ Difference between Density and Relative density

❻ Calculations involving Density and how to apply it in reality

❼ A better understanding of Upthrust

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   A better understanding of Density

    Have you ever held a litre of petrol and a litre of kerosene? Did you notice any difference in weight? What about the 25 litres of water keg and 25 litres of palm wine? I believe you must've that's if you ever got to try it out.  

    The litre is a method of quantifying VOLUME. A litre of petrol and a litre kerosene has the same volume but yet different weight, this is where DENSITY comes into Play. To understand Density properly, you need to understand the difference between VOLUME, MASS AND WEIGHT. 

    MASS is the amount of particle contained in matter, VOLUME is the amount of space occupied by matter or a substance while WEIGHT is the force of attraction the 🌎earth use in pulling a substance or body or matter  towards the earth🌍. ⬆️ If these explanation are unclear to you please notify me in the comment box ⬇️.

    Density is the amount of mass or the mass in a unit volume of a substance. The formula is written like this;

                              ρ=m

                                  ‾‾‾

                                   V

                            Density =      Mass

                                               ‾‾‾‾‾‾‾‾‾‾‾‾

                                                   Volume

                             ρ = Kg

                                   ‾‾‾‾‾‾

                                   m³

                            ρ = Kg/m³ or kgm-³

Water is dense than petrol because a litre of water has more mass and weight than a litre of petrol, do you understand this now dear friend?

Other units of volume is the Cm³ , m³ , dm³ e.t.c.

    You have to understand that;

         ⇒ 1000 Cm³ is 1 litre

         ⇒ 1000,000 Cm³ which is 1000 litres is 1 m³ 

Also, g/cm³ may be used in most cases. And not forgetting also that kg meaning kilogram is 1000 g.

  Density of common materials and substances

    Now let's look the density of some materials we know of in nature and might have probably seen in reality.

Aluminium          2.7 × 10³ kgm-³   or    2.7 g/cm

Water(at 4℃)     1 × 10³ kgm-³       or       1 g/cm

Iron                       7.9 × 10³ kgm-³   or   7.9 g/cm

    Take that of aluminum, the value of aluminum means 2700 kgm-³ i.e after multiplying 2.7 by 10^3(which is 1000). It means that in 1 m³ of aluminium, the amount of atoms which are the particles have all together have a mass of 2700 kg or you can say that in every 1 m³ of aluminum there is  a mass of 2700 kg or you can also say that 2700 kg of aluminum has a volume of 1 m³. The same applies to water and iron.

    Let's take water 🌊🌊🌊, the value tells that 1000 kg of water has a volume of 1 m³ or in every 1 m³ of water there is a mass of 1000 kg. Also if you measure 1 cm³ of water in a test tube, you have one gram of water since water's Density is also 1 g/cm.

      Relative Density

    Relative Density(R.d) is the mass(or weight) of a substance divide by the mass(or weight) of water that has the same volume if that substance.

Water is chosen because it is the most common liquid. You therefore say that Relative Density is;

  R.d = mass(or weight) of a substance

             ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

           mass(or weight) of equal volume of water

Also,

     R.d = density of substance

                ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

               density of water

          How to determine or find the density of a material or substance

    It's very easy is to know the density of a substance. Let's take your Android smartphone for example. You want to know it's density, all you need to do is take a ruler and measure it's length, breath and height and multiply using the formula L x B x h, to get the volume. Then you measure it's mass on a weighing scale. 

    Let's say the mass is 59 g and the volume is 245 cm³, then the density of your phone is;

        ρ = 59

             ‾‾‾‾‾

             245

        ρ = 0.241 gcm-³ 

which means that if you break your phone to pieces,  a piece of 1 cm³  will weigh 0.241 g. Also, to get the density in kgm-³ you multiply by 10³ which will give you 0.24 x 10³ kgm-³.  

    If the object's shape is irregular, take for example a stone. Fill a beaker to the brim and put the stone inside, the water that spills out is the volume. Then measure the mass of the stone using a scale and use density formula to know the density.

         Difference between Density and Relative density

    With the definition of Density and Relative density, you should now know the difference between the both of them.

    Density is the amount of mass or the mass in a unit volume of a substance, while Relative Density(R.d) is the mass(or weight) of a substance divide by the mass(or weight) of water that has the same volume if that substance. 

          Calculations involving Density and how to apply it in reality

    Now let's take some calculations to finalize Things in density.

Example 1:

A relative density bottle 🍼weighs 20 g when empty, 80 g when filled with water and 100 g when filled with a liquid. Find the relative density of the liquid.

              Solution

First find the mass of the liquids;

⇒Mass of bottle = 20 g

⇒Mass of bottle filled with water = 80 g

⇒Mass of water = 80 g - 20 g = 60 g

⇒Mass of Unknown liquid = 100 g - 20 g = 80 g

R.d = mass(or weight) of a substance

             ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

           mass(or weight) of equal volume of water

R.d = 80 g

          ‾‾‾‾‾‾‾

           60 g

R.d = 1.33

Example 2:

A metal of density 9000 kgm-³ weighs 60 N, find it's volume.

          Solution

First get the mass from the weigh by dividing weigh by 10;

     Mass = 60 N

                   ‾‾‾‾‾‾‾

                       10

  Mass = 6 kg

Now,

     Density =      Mass

                          ‾‾‾‾‾‾‾‾‾‾‾‾

                              Volume

 9000 kgm-³ =    6 kg

                            ‾‾‾‾‾‾‾‾‾

                             Volume

Cross multiply,

   Volume x  9000 kgm-³ = 6 kg

Divide both sides by 9000 kgm-³

    Volume =    6 kg

                       ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

                       9000 Kgm-³

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Conclusion

Now, I believe that you 👍now understand density and Relative density, although I will release more calculations on density. Send your questions to me and get them replied as soon as possible and also don't forget to watch the video🎥📺 for the post through the link below at the end 👇 of this post. Next is Upthrust, in order not to make this post lengthy, I will Create a new post for Upthrust, so please please please stay tuned for more…

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Semiconductors

Semiconductors are materials that have properties in between that of a normal conductor and that of an insulator.

#1.2 Properties Of A Semiconductor

A semiconductor resistance decreases as its temperature increases, unlike metals whose resistance increases with increase in temperature.
Semiconductors have a crystalline structure of four valence electrons.
Example of common semiconductors are silicon and germanium.

#1.2.2 Electrons And Holes

When a semiconductor is at the lowest possible temperature, in the atom all the the electrons are firmly bounded to the nucleus, there are no free electrons. But when at room temperature thermal energy will be acquired by the electrons, if the thermal energy acquired is stronger than the energy binding the electrons to the nucleus, the electrons breaks free from the bond and becomes a 'free electron' by moving out of its position in the atom leaving a vacany called a hole which is equivalent to a positive charge +e.
An electron in a near by atom will be attracted to fill this hole create.
If this semiconductor is connected to a battery, the holes will move towards its negative terminal and the electrons will move towards the positive terminal.
All pure semiconductors have equal number of holes and electrons.

#1.3 Doping Effect

Doping is the adding of impure materials into pure semiconductors to alter the structure of the semiconductor crystal.
#1.4 n - type Semiconductor
A n - type semiconductor is produced by adding an element such as arsenic or antimony to a germanium semiconductor.
This produces more electrons in the semiconductor making it have negative charge.
#1.5 p - type Semiconductor
A p - type semiconductor is produced by adding an element such as indium or boron to a silicon semiconductor.
This produces more holes in the semiconductor making it have positive charge.

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