Newton's Laws of Motion

len Alfred Ajibola - Tue, 24th December, 2019 @ 14:16: 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

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The Law of Inertia is also referred to as _____.

  • A. 1st Law of Thermodynamics
  • B. 2nd Law of Thermodynamics
  • C. 3rd Law of Thermodynamics
  • D. Newton's 1st Law of Motion
  • E. Newton's 2nd Law of Motion
  • F. Newton's 3rd Law of Motion

The process whereby the velocity of an object increases and decreases over a period of time is best associated with the term _____.

  • A. Speed
  • B. Velocity
  • C. Momentum
  • D. Constant Velocity
  • E. Acceleration
  • F. Average Velocity

The rate of motion is best referred to as _____.

  • A. Speed
  • B. Velocity
  • C. Momentum
  • D. Inertia
  • E. Acceleration
  • F. Constant Velocity

Consider this expression below:

A body X exerts a force FX on another body Y. In return, body Y exert a force FY back on body X. The forces FX and FY are equal in magnitude but opposite in direction.

Putting the above expression into equation:

FX = -FY

Where FX is the action force

FY is the reaction Force

The above expression relates to _____.

  • A. Theory of Force
  • B. Force Postulate
  • C. Einstein's proposal on Relativity
  • D. Newton's 1st law of motion
  • E. Newton's 2nd law of motion
  • F. Newton's 3rd law of motion

The tendency of a body to remain in a state of rest or in uniform motion is referred to as _____.

  • A. tension
  • B. uniform acceleration
  • C. constant acceleration
  • D. deceleration
  • E. inertia
  • F. velocity

A change in the position of an object with reference to time is best described as _____.

  • A. momentum
  • B. displacement
  • C. velocity
  • D. acceleration
  • E. direction
  • F. motion

The saying "what goes up on earth must come down" can be best attributed to _____.

  • A. force
  • B. motion
  • C. mass
  • D. acceleration
  • E. average velocity
  • F. constant velocity

We have _____ laws of Thermodynamics.

  • A. 1
  • B. 2
  • C. 3
  • D. 4
  • E. 5
  • D. 6

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Newton's Laws of Motion:

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:

1. Newton's First Law of Motion

2. Newton's Second Law of Motion

3. Newton's Third Law of Motion

Note: 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.

  • Newton’s First Law of Motion

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.

Please read on Motion and Speed here.

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 at rest while another in uniform motion will keep moving in a straight line.

Note: Think of inertia as being resistant to change.

Inertia is a property of matter.

It was Newton’s first law of motion that shows the presence of inertia in a body at rest (or in a body moving with a constant velocity).

Please read on the Basic and Fundamental Physics Concepts here.

Note: Matter is anything that has mass and occupy space. Mass is a measure of inertia; thus the bigger the mass of an object, the more inertia the object would have.

Please read on the Concept of Matter here.

In conclusion, 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 the Force of Gravity (in relation to Mass) here.


  • Newton’s Second Law of Motion

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.

Think of momentum as mass in motion; that is, the quantity of motion a moving body has.

Momentum is the product of mass and velocity.

You may have heard the commentator of a football match commenting that “a team has gained momentum”. This will simply imply that the team is on the move or pressing high.

Please read on Velocity and Acceleration here.

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.

This 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 for instance, 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.

Note: 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

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 actually 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.

Note: Playing football 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 exist almost on everything that has mass. It is also often seen and encountered in a wrestling match.

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, the body B will in return exert an equal and opposite force FB back 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

Where FA is the Action Force

FB is the Reaction Force

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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

Image Credit: Ball and Roller Store

Glass Balls actually 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/s2Please read on gravity here

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.
Please read on motion, speed, velocity and acceeration 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.

The study of Thermodynamics revolves around the relationship between heat, temperature, energy and mechanical work; and these can be summarised under the 4 laws of Thermodynamics (Numbered zero through three).

You can read on the Concepts of Heat and Temperature here.

Below are the 4 laws of thermodynamics:

Zeroth law of thermodynamics – If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

Please read on the Zeroth Law of Thermodynamics here.

1st law of thermodynamics – Energy can neither be created nor destroyed but can be changed from one form to another.

You can read on the Food Chain here.

2nd law of thermodynamics – The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.

3rd law of thermodynamics – As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

Fuses are present in many electrical devices. They are basically 🔥 fire-breakers 🔥

If there is a power surge, the fuse will break, preventing damage to the electrical devices. It will also prevent the incidence of 🔥 fire🔥 on/from such device.

Physics is one of the core sciences.

Physics is defined the scientific study of matter and the movement of matter through the space and time of the universe.

Understanding the basic and fundamental concepts of physics will help you better comprehend this subject. Below are some of the concepts:

  1. The Laws of Motion (Classical Mechanics)
  2. Electromagnetism
  3. Relativity
  4. Thermodynamics

Please read on the basic introduction of the above physics concept here