Alfred Ajibola
- Thu, 14th March, 2019 @ 12:04 PM
Topics in Physics
Derived 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 PhysicsAcademic Questions in Physics
Which of the following is a fundamental quantity?
A. Luminous Intensity
B. Area
C. Volume
D. Velocity
E. Concentration
F. Acceleration
An object at rest will temporarily stay in its state of rest, and if the object is in uniform motion, it will temporarily move in a straight line, unless an external force acts upon it.
The above statement refers to Sir Isaac Newton's first law of motion.
A. True
B. False
Which of the following statement is incorrect concerning gravity?
A. The force of gravity is generally considered the strongest force among the four forces that govern the universe
B. Your weight changes as you travel away from the earth
C. If we dig the earth until we get into its center, we will have no weight as a result of lack of gravity
D. Gravity prevents us from falling off the constantly rotating earth
E. If a hammer and a feather are dropped simultaneously in a vacuum, they will both land at the exact same time as a result of gravity
F. Weight is always a function of gravity
Sir Isaac Newton was hit by an apple when he pondered on force, motion and gravity.
A. True
B. False
The movement of gaseous particles through a tiny hole is termed _____.
A. Osmosis
B. Diffusion
C. Effusion
D. Infusion
E. Defusion
F. Gaslusion
A lighted bulb transfers heat through a process termed _____.
A. Conduction
B. Convection
C. Radiation
D. Oxidation
E. Reduction
F. Electrical Induction
A measurement of how much the velocity of an object changes with time is termed _____.
A. Displacement
B. Acceleration
C. Speed
D. Momentum
E. Velocity-Time graph
F. Average velocity
Which of the following differentiates velocity from speed?
A. Distance
B. Time
C. Momentum
D. Inertia
E. Direction
F. Distance and Time
Before the zeroth law of Thermodynamics was put forward, there had already existed 3 laws of Thermodynamics. These are:
Scientists came to a realization that these 3 sets of laws are incomplete with regards to temperature. They envisaged the need for a law that will introduce a formal definition of temperature.
Due to the nature and importance of this law, it needed to supersede the three existing laws. At that time, the three laws (named respectively as 1st, 2nd and 3rd laws of Thermodynamics) were already popular in the academic world. Since these three laws are widely known by their numbers, a numbering confusion came up.
An alternative of calling this new law 'the fourth law of Thermodynamics' wouldn't be ideal due to its position and importance. It was a scientist named Ralph Fowler who termed the new law 'Zeroth Law'. This was a naming caveat that has become popular to this very day.
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.
To better understand what the zeroth law meant, we need to comprehend 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 imply 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.
Please read on heat transfer here
When we put a pot of water on a cooking gas, we will notice the transfer of heat from the cooking gas to the pot and subsequently, the water. The water begins to get warm during this process.
As heat transfer continues, the water becomes warmer and eventually becomes hot. A point will be reached when the water starts to boil. Recall that the boiling boiling point of pure water is 100OC.
Thermal equilibrium for the pure water is reached at 100OC because the water cannot become hotter through boiling; instead, it evaporates as water vapour.
Although, temperature is not directly mentioned in the zeroth law, the law actually points us towards the existence of temperature as a quantity.
It can therefore be stated that temperature is the quantity that remains constant (the same) for all systems in thermal equilibrium.
The above explanations are summarized in the image below:
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Amazing facts in Physics
A medium-sized cumulus cloud has a weight of about 80 adult elephants.
You can think of cumulus cloud as a detached, individual, cauliflower-shaped cloud often seen in fair weather conditions
The reason the Leaning Tower of Pisa is tilted is the same reason it's still standing
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
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. It 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.
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 constantly 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).
Heat is a form of energy. It cannot be lost according to the first law of Thermodynamics; rather it will be transferred. The first and second laws of thermodynamics are stated below:
Energy can neither be created nor destroyed but can be transformed or converted from one form to another.
1st law of thermodynamics
In the course of energy transfer, some energy is lost in the form of heat to the surroundings.
2nd law of Thermodynamics
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:
The temperature of water inside the aluminum cup will begin to decrease from its initial 100OC.
The temperature of the aluminium cup will increase from its previous 22OC.
After some time, the temperature of the water, aluminium cup and the surrounding will become the same.
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 (water and aluminum cup) together with the surrounding reaches the same temperature; and the heat transfer ceases. It is at this point that the water, aluminium cup and the surroundings are said to have reached a thermal equilibrium.
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 will simultaneously decrease 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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