Topics in PhysicsDerived Units: Similarities and Differences with Fundamental Units Gravity: Interesting facts on Gravity Relative Density of Substances and Specific Gravity Types of Heat Transfer: Conduction Types of Heat Transfer: Convection Types of Heat Transfer: Radiation Physics Scheme of Work, SS1, First Term Physics Scheme of Work, SS1, Second Term Physics Scheme of Work, SS1, Third Term Velocity and Acceleration Newton's Laws of Motion Importance of Gravity What is Density? Density of various Substances Concepts of Force and Motion Motion and Speed Concept of Heat Transfer Concepts of Heat and Temperature Gravity: What is Gravity? Zeroth Law of Thermodynamics - Thermal Equilibrium Fundamental Quantities and Units in Physics
Academic Questions in Physics
A natural force that pulls a body towards the center of the earth is termed _____.
A. Centripetal force
B. Centrifugal force
C. Black hole
D. Average acceleration
A Greek letter that expresses density is _____.
A glass of water has a higher density than an exact glass of oil.
An 🍎 apple 🍎 falling from a tree has an unbalanced force.
Force is a quantity measured in _____.
D. Meter per second square (ms-1)
Heat transfer indicates two systems of varying temperatures and will always be transferred from a region with lower temperature to another with higher temperature.
Heat can be created.
Temperature is defined as the measure or ability of an object or substance to transfer heat energy to another object or substance.
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Let's begin by considering the instance below:
If we have water of 100OC in an aluminium cup whose temperature is the same as that of its surrounding; let’s say 22OC; We will observe the followings:
Note: OC = degree centigrade; and it's a unit of temperature.
For now, think of temperature as the degree of hotness or coldness of a substance or an object with reference to some standard value.
From the above instance, it can be deduced that the heat present in the water molecules are first transferred to the aluminium cup and subsequently to the surrounding.
Heat from water >>> Aluminium Cup >>> Surrounding
Meanwhile, understand that aluminium is a metal; and metals are good conductors of heat.
Eventually, the system and the surroundings will reach the same temperature; and the heat transfer ceases. It is at this point, that the water, aluminium cup and the surrounding are said to have reached a thermal equilibrium. This concept of thermal equilibrium is a function of the zeroth law of thermodynamics.
Although the surrounding receives heat from the water and aluminium cup, it is noteworthy to state that the surrounding's temperature will remain approximately unchanged for the following reasons:
Heat is never lost because it is a form of energy. Instead, it will be transferred according to the first law of Thermodynamics which states that:
Energy can neither be created nor destroyed but can be transferred from one form to another. You can read on food chain here.
Note: From the above explanations, the transfer of energy (heat energy in this case) from the water to the aluminium cup and finally to the surrounding is referred to as heat.
Heat can simply be explained as an energy that results from the transfer of energy from an object or substance or system with a higher temperature to another with a lower temperature.
Let consider a reverse instance with regards to heat:
Now, imagine that a cold bottle of water is brought out of the fridge into the kitchen. Assuming the temperature of water is 3OC while that of the kitchen environment is 22OC; the followings will occur:
Note: At no point did the coldness of the bottle or water escaped into the surrounding. Instead it is the temperature of the room that actually caused an increased temperature of the bottle and water (inside the bottle).
In fact, if the temperature of the room was higher 22OC, heat transfer will be achieved at a much rapid rate. (That is; the rate at which the temperature of the water and bottle increases will be faster).
Since heat energy is being transferred from the kitchen surroundings to the bottle and then into the water; We can therefore conclude that heat will always be transferred from a higher region to a lower region until equilibrium is attained.
Heat is never static. It is always transferred and thus; an object will increase its temperature by gaining heat energy from its surroundings while another object simultaneously (at the same time) decreases its temperature by losing its heat energy to the surroundings. For this reason, we may also define temperature as:
The measure or ability of an object or substance to transfer heat energy to another object or substance.
The higher the temperature, the greater the ability of an object or substance to transfer heat. Conversely, the lower the temperature, the greater the tendency of an object to receive the transferred heat.
The point is: 'for heat to be transferred, we must have systems or objects or substances with varying temperatures.
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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.
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Amazing facts in Physics
One quarter of an apple is filled with air and that's why they float in water
The Nobel price was named after its founder, Alfred Noble. He is a Swedish, born on October 21, 1833; and was the inventor of dynamite. He was also a a famous scientist and a successful business man.
Glass balls bounce higher than rubber balls
Every planet has its own unique gravitational force. For instance, Mars has a gravity of 3.711 m/s2 while earth’s gravitational force is 9.807m/s2.
When two metals are put together in space, they will stick together as if they are welded. This phenomenon is called cold welding
The fastest animal on land is cheetah. It can reach a maximum speed of about 113km per hour.
NOTABLE POINTS IN Physics
The earth is governed by the force of gravity and that’s why everything present on it (humans, plants, animals and even air) is always drawn towards it. You will actually need some form of force greater than gravity in order to pull yourself away from the earth.
As an instance, the earth as we know is spherical in shape and held in space. Also, all humans live on a constantly rotating earth and not inside the earth. Since we live on a spherical earth held in space, how come humans are yet to fall off the constantly rotating earth?
Well, the answer is gravity. Even if we attempt to jump off the earth into space, the force of gravity present on earth will still pull us down. In fact, in order to leave the earth; there has to be a force stronger that gravity; which must be applied to whatever is attempting to leave the earth. For this reason:
Whenever one jumps, a certain amount of force is needed to be applied by that person. However, gravity still return the person back to earth because the applied force had been exhausted.
The larger the size of an object, the greater it’s force of gravity. Gravity is therefore affected by the size and closeness of objects.
Since the earth is larger than the moon, it will have a greater gravitational force than the moon. We will be more attracted on the earth than we would on the moon if we were astronauts on the moon. This implies that we will weigh differently on both places. For this reason, our weight will also vary on the various planets (because they are of different sizes). This is shown in the diagram below:
Weight depends on the degree at which the gravity on earth or moon or another planet pulls an object while the Mass of any object or body will always remain the same (constant) since it’s the amount or quantity of matter in the body.
To better understand the Zeroth Law of Thermodynamics, we need to know what thermal equilibrium is. This is explained below:
Two bodies A and B are said to be in thermal equilibrium if each body can transfer heat to each other when placed closed together but ended up not transferring any heat to each other.
This will mean that both bodies are at equal temperature.
Now, according to the zeroth law, assuming we have three bodies namely X, Y and Z:
If X = Y and Z = Y, then X = Z
From the above expression, it will be observed that: if X and Y are in thermal equilibrium and Z and Y are in thermal equilibrium, therefore, X and Z must be in thermal equilibrium too.
So we can see that according to the zeroth law, temperature is a quantity worth measuring.
It can therefore be said that temperature is the quantity that remains constant (the same) for all systems in thermal equilibrium.
Consequently, the zeroth law of Thermodynamics states that if two separate bodies are in thermal equilibrium with another body, then they are also in equilibrium with each other
Fundamental units are the units of fundamental quantities.
A fundamental unit is a unit that does not depend on any other unit; neither can it be changed nor is related to another fundamental unit.
A fundamental unit is also referred to as a basic unit.
Fundamental Units are always constant. This means that they don't change, (remains the same) and are standardized all over the world.
The fundamental quantities alongside their respective fundamental units are 7 in number. They include:
Mass (m) is a fundamental quantity whose unit is kilogram (kg)
Length (l) is a fundamental quantity whose unit is meter, (m)
Time (t) is a fundamental quantity whose unit is second (s)
Temperature (T) is a fundamental quantity whose unit is Kelvin (k)
You can read on the Concept of Temperature and Heat here.
Electric Current (I) is a fundamental quantity whose unit is ampere (A)
Amount of Substance (n) is a fundamental quantity whose unit is mole (mol)
Luminous Intensity (|v) is a fundamental quantity whose unit is candela (cd)
The classical mechanics (laws of motion) is a fundamental part of Physics.
Below are the Newton's laws of motion:
An object at rest will continue in its state of rest; while an object in uniform motion will continue in a straight line, unless an external force acts on it.
Newton's first law of motion.
The rate of change of momemtum is proportional to the applied force and will take place in the direction of that force.
Newton's second law of motion.
To every action, there is an equal and opposite reaction.
Newton's third law of motion.