Physics

Concepts of Force and Motion

len Alfred Ajibola - Thu, 11th July, 2019 @ 3:00 PM

Topics in Physics

Derived 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

Please check out our Test Your Knowledge page to see all Questions and Answers

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

  • E. Gravity

  • F. Momentum

A Greek letter that expresses density is _____.

  • A. Alpha_d

  • B. Beta_d

  • C. Theta_d

  • D. rho

  • E. dho

  • F. dhr

A glass of water has a higher density than an exact glass of oil.

  • A. True

  • B. False

An 🍎 apple 🍎 falling from a tree has an unbalanced force.

  • A. True

  • B. False

Force is a quantity measured in _____.

  • A. Kilogram

  • B. Gravity

  • C. Incandescence

  • D. Meter per second square (ms-1)

  • E. Mole

  • F. Newton

Heat transfer indicates two systems of varying temperatures and will always be transferred from a region with lower temperature to another with higher temperature.

  • A. True

  • B. False

Heat can be created.

  • A. True

  • B. False

Temperature is defined as the measure or ability of an object or substance to transfer heat energy to another object or substance.

  • A. True

  • B. False

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Concept of Force:

Force is a vector quantity because it has both magnitude and direction.

By definition, any form of push or pull acting on an object is termed force.

You probably may have heard a saying that goes thus:

  • what goes up must come down.

The above statement is true because the earth has a force acting upon it. This force, (called the gravitational force of the earth) acts by pulling all things towards the earth.

In order to move away from the earth, there must be another constant force acting on an object that attempts to exit earth's surface. This force must be greater than the earth's gravitational force (or force of gravity). For this reason, aeroplanes and jets move away (fly) from the earth and remains in the sky because the constantly applied force on them is greater that the earth's gravitational force.

Please read more on gravity here.

In another instance, when you jump, you apply a force. However, since this applied force isn’t constant, the force of gravity present on earth eventually bring you back to earth's suface.


Force as a quantity is measured in Newton (N). This is in honor of Sir Isaac Newton for the great work he had done.

Please read on fundamental and derived units here.

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. To summarize this:

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.

You can read on velocity and acceleration here.

 

Force and Motion:

Sir Isaac Newton presented the laws of motion which was accredited to his name in 1968. These motion laws of Newton explains the relationship between the forces acting on a body and the motion of the body.

Recall that motion refers to a change in the position of an object with reference to time.

Please read on motion and speed here.

As an instance, a pen resting on a table will continue to remain on the table unless it is pushed or pulled by something. This push or pull with the tendency of making the pen move away from its exact position is termed force.

Please read on the importance of gravitational force here.

Force exists as a result of an interaction between two objects. From the above instance, if nothing interacted with the pen on the table, then the pen will continually remain on the table.

If there is no interaction between objects, force will never be experienced.

You can read on the fundamental physics concepts here.

With the above explanation on force and motion, we can now understand more easily the Newton's laws of motion.

Please read on Newton's laws of motion here.

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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

Alfred Noble - Len Academy

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 Ball - Len Academy

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.

Please read more on the concept of gravity here.

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:

Weights on planets - Len Academy

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.

Please read on mass versus weight here

Zeroth Law - Len Academy

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

Please read more on the zeroth law of thermodynamics here

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:

  1. Mass (m) is a fundamental quantity whose unit is kilogram (kg)

  2. Length (l) is a fundamental quantity whose unit is meter, (m)

  3. Time (t) is a fundamental quantity whose unit is second (s)

  4. Temperature (T) is a fundamental quantity whose unit is Kelvin (k)
    You can read on the Concept of Temperature and Heat here.

  5. Electric Current (I) is a fundamental quantity whose unit is ampere (A)

  6. Amount of Substance (n) is a fundamental quantity whose unit is mole (mol)

  7. Luminous Intensity (|v) is a fundamental quantity whose unit is candela (cd)

Please read more on fundamental units here

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.

Please read on motion and speed here.

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.

Please read on Newton's laws of motion here.