Motion, Speed, Velocity and Acceleration

len Alfred Ajibola - Thu, 27th June, 2019 @ 14:48: PM

Topics in Physics

Density and Specific Gravity Force and Motion - Newton's Laws of Motion Motion, Speed, Velocity and Acceleration Heat Transfer, Conduction, Convection and Radiation Concept of Heat and Temperature Gravity explained with some fun facts Zeroth Law of Thermodynamics - Thermal Equilibrium Explanation, Similarities and Differences between Fundamental and Derived Units Physics - Basic and Fundamental Physics Concepts

Academic Questions in Physics

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

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


Motion happens to be 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:

  • The earth orbits or revolves round the sun.
  • The moon revolves round the earth (as earth’s satellite).

Please read on the Solar System here.

In physics, motion refers to a change in the position of an object with reference to time.

Although we may 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 instance, 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.

Another instance can be attributed to someone sitting inside a moving bus. The person will appear to be static (not moving). Based on the fact that the bus is in motion (moving), we can conclude that the motion of the person sitting inside the bus is relative to the bus.

Please read on the Basic and Fundamental Physics Concept here.

Note: Force is responsible for the motion/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 "forever" unless it is acted upon by a force. This force could be in the form of an applied air or a deliberate touch by humans.

Please read on Gravity explained with some Fun Facts here.

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:

1. Speed

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 10000 meters in 50 seconds and another covers the same distance in 5000 seconds, we can conclude that the first person has a faster speed than the second person 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

Note: Distance is the total length of path traveled from one point to another. It is measured in meters (m).

Time is a duration or period during which things happen. It is measured in seconds(s).

Speed is a scalar quantity since it is has only magnitude and no direction.


2. Velocity

Although velocity and speed are often used interchangeably by students, they are NOT the same thing.

The direction in which an object is moving is what differentiates velocity from speed.

Velocity can be defined as speed in a given direction.

Velocity can also be defined as the rate of change of displacement.

It is a vector quantity because it has magnitude and direction

Velocity = Change in distance/Change in time

Below is a narrative that differentiates speed from velocity:

A bus is moving on a highway at a speed of 100 meters per 20 seconds. If the bus changes its direction and moves at a different speed (or even the same speed), then that's velocity.

As an instance, the bus (above) may move at a velocity of 100m/20s in the northern direction and 200m/20s in the eastern direction.

Note: Speed and velocity both have the same Standard International (SI) unit which is meter per second (m/s).

Please read more on Fundamental and Derived Units here.


3. Acceleration

The velocity of a moving object can either decrease or increase over a period of time; and this is where acceleration comes into play. Consider the instance below:

When you ride a bicycle, you start slowly but as soon as you increase the push on the pedals, the bicycle moves faster (accelerate). When you stop pushing the pedals, the bicycle begins to move slowly (negative acceleration).

From the above instance, we can therefore say that acceleration can also be negative.

Note: Deceleration is an English term used to describe negative acceleration; but in physics, we use the term acceleration to denote both the positive and negative changes in velocity.

Please read more on Synonyms with various Examples here.

Acceleration can be defined as the rate of change of velocity.

Acceleration is also defined as the measurement of how much the velocity of an object changes with time.

Acceleration = Change in velocity/Change in time

If an object changes velocity after a fixed amount of time, then such acceleration is said to be constant (that is: constant acceleration).

Consider the instance below:

If we throw a table tennis ball down a slope, it will roll downwards more rapidly at each second.

On the 1st second, let's assume it's velocity to be 20m/s.

On the 2nd second, its velocity becomes 25m/s.

On the 3rd second, it becomes 30m/s.

With regards to the above velocities, such ball is said to have a constant acceleration of 5m/s.

This means that: for every 5 meters moved, the tennis ball accelerates by 1 second.

Note: Average acceleration is the total change in velocity over a period of time, divided by the duration of that period.

Acceleration is a vector quantity and its Standard International (SI) unit is meter per second (m/s) or meter per second square (m/s2).

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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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