Topics in PhysicsDerived Units: Similarities and differences with fundamental units Gravity: 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 in Physics Motion and Speed in Physics Concept of Heat Transfer Concepts of Heat and Temperature What is gravity? Concept of gravity on the solar system 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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Motion is considered by many as one of the interesting topics in physics. Generally, an object is said to be in motion whenever it moves. In fact, we live in a universe where everything moves, although at a different rate. For instance:
In physics, motion is defined as a change in the position of an object with reference to time.
Although we sometimes sit or stand in a fixed position, that doesn’t mean motion isn’t taking place. The fact that the earth is rotating implies that we are indirectly moving along with it. We can thus say that motion can be relative to some frame of reference.
In the above paragraph, the earth (constantly rotating along its axis) is our frame of reference and everything present on earth is in motion (with regard to earth as a frame of reference).
In another instance, a person statically seated in a moving bus also undergoes motion. Although such person appears to be static (not moving); but since the bus is in motion (moving), we can correctly conclude that the motion of the person sitting inside the bus is relative to the bus.
Force is responsible for the motion or movements present in the universe.
For an object to move, a force must act upon it. Consider the instance below:
If we keep a pin in a vacuum and it’s left untouched, the pin will remain in that position unless it is acted upon by a force. This force could be in the form of an applied air or a deliberate touch.
In order to get a better understanding of motion, it is important we know how the following terms work since they all involved in motion. The terms are:
Speed is simply the rate of motion since it is a measure of how fast or slow an object is moving. The dimensions associated with speed are distance and time.
If one covers a distance of 10,000 meters in 50 seconds and another covers the same distance in 5,000 seconds, we can conclude that the first person has a greater speed because he covered the same distance at a lesser time.
Speed is defined as distance travelled per unit of time.
Speed can also be defined as the rate of change of distance.
Speed = distance/Time
Speed is a scalar quantity since it has only magnitude. Speed does not have a direction.
Time is a duration or period during which things happen. It is measured in seconds(s).
Distance is the total length of path traveled from one point to another. It is measured in meters (m).
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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.