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 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
Motion can be defined as a change in the position of an object with reference to time.
We have 3 laws of motion as postulated by Sir Isaac Newton in 1687. These are:
Newton's First Law of Motion
A good knowledge on the concept of force will aid you to better understand the above laws.
Please read on the concept of force and motion here.
Also known as 'law of Inertia', Newton’s first law of motion states that:
An object at rest will continue to stay in its state of rest, or if the object is in uniform motion, it will continue to move in a straight line, unless an external force acts on it.
When no force is applied to a body, the tendency or outcome of the body to remain in a state of rest or in a uniform linear motion is known as inertia.
The concept of inertia implies that an object at rest will continue to remain in a state of rest while another in uniform motion will keep moving in a straight line as far as the object isn't acted upon by a force.
You can think of inertia as being resistant to change. Meanwhile, understand that inertia is a property of matter.
It was Newton’s first law of motion that showed the presence of inertia in a body at rest (or in a body moving with a constant velocity).
You can read on the basic and fundamental physics concepts here.
Recall that matter is anything that has mass and occupy space. Also, mass is a measure of inertia. In this regard, the larger the mass of an object, the more inertia the object would have.
Please read on the concept of matter here.
In summary, the law of inertia which is a reference to Newton’s first law of motion summarizes what force can do in relation to mass.
Please read more on gravity (in relation to mass) here.
Newton’s second law of motion states that the rate of change of momentum is proportional to the applied force and will take place in the direction of that force.
You can think of momentum as mass in motion; that is, the quantity of motion a moving body has. You may have heard a commentary on a football match stating that a team has gained momentum. This will imply that the team is on the move or pressing high.
Momentum is the product of mass and velocity.
When we apply the second law of motion to reality, it will help us determine the amount of force needed to make an object move or stop.
The second law is applied in various field of sports including football, basketball and cricket.
Please read on motion and speed here.
In the game of cricket, the players will usually pull back their hands when catching the ball. This is so because pulling back the hands increases the time of contact with the ball, thus resulting in less jerk from the motion of the caught ball.
Through Newton’s second law of motion, we are able to define an absolute unit of force which remains constant under a moving condition.
Also, the second law of motion gives us the operational definition of force as the rate of change of momentum with time.
Newton's third law of motion states that action and reaction are equal and opposite.
The third law can also be stated thus: 'To every action, there is an equal and opposite reaction.
Consider the instance below:
When a boxer blows a wall, he will in return feel a reverse force on his hands.
Although the boxer exerts a force on the wall (in the above instance), the wall in return exerts an opposite force on hands of the boxer. Based on this fact, the boxer may feel some pain on his hands depending on the nature of the wall and the degree of force exerted on the wall.
Also, playing a football match without boots might get you injured when you kick a player. This is so because there is a reverse force from the kicked player.
Newton’s third law exists on everything that has mass. It is also seen and encountered in wrestling matches.
Please read on the differences between mass and weight here.
According to the third law of motion, if a body 'A' exerts a force FA on another body 'B', body B will in return exert an equal and opposite force FB on body A. The forces FA and FB are therefore equal in magnitude but opposite in direction.
We can therefore write the above expression as:
FA = -FB
From the above, FA is the action force while FB is the reaction force.
Kindly share this article via the links below:
Please click here to contact Alfred if you require any of the following services:
If you need a standard website at an affordable price.
Online training on the academic subjects: biology, chemistry and basic science.
If you require an advanced smart school management system (web application) for your school.
Click here to read on Len Academy Smart School Software.
Please click here to follow Len Academy on Google News.
Amazing facts in Physics
Marie Curie was the first person ever to win two Nobel prizes. She won her first Nobel price for physics in 1903, and the second for chemistry in 1911 for her work on radioactivity.
The hottest temperature ever recorded occurred in Furnace Creek Ranch, Death Valley, California, USA, at 56.7oC or (134oF) on July 10, 1913
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
The Standard International (SI) unit for density is kilogram per cubic metre (Kg/m3).
The table below shows various substances with their densities:
|
Substance |
Density (Kg/m3) |
|
Helium |
0.179 |
|
Air (1atm and 20oC) |
1.20 |
|
Bamboo Wood |
400 |
|
Ethanol |
810 |
|
Methylated Spirit |
800 |
|
Benzene |
900 |
|
Paraffin Wax |
900 |
|
Ice |
920 |
|
Water (Fresh Water) |
1000 |
Force can be balanced or unbalanced.
When forces from different directions act on an object and consequently bring about the object's motion, then such forces are unbalanced.
Conversely, if theses forces bring about zero motion (static position or no movement) on the object of reference, then it's a balanced force.
In summary,
An apple hanging on a tree (without any form of movement) has a balanced force.
An apple falling from a tree has an unbalanced force.
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