Is Deceleration Negative: Detailed Facts


We are familiar with the word deceleration. In this article, we will know the different aspects of deceleration negatively in detail.

Deceleration is a phenomenon that is opposite to acceleration. It comes to play when there is a sudden reduction in the body’s velocity; since it reduces the fastness, it is a negative acceleration and is plotted on the negative side of the coordinate system. Deceleration has a negative value.

Now let us focus on the various insights of is deceleration negative in detail.

Is deceleration always negative?

Deceleration is sometimes referred to as negative acceleration indicating its direction.

In general, deceleration acts in the opposite direction to the direction of velocity; in this case, the velocity will be positive and the deceleration negative. If the velocity is in the same direction as deceleration, it has a positive value.

Now let us know if deceleration is a negative number.

is deceleration negative
Image: Deceleration

Can deceleration be a negative number?

If it has a negative value, it can be a negative number.

The deceleration can be a negative acceleration but not a negative number. Since it acts opposite to the motion of a body, it comes to exist only during a sudden decrease in velocity. We can say that it can occur in any direction and can have a negative number only when it is considered negative acceleration.

Now it’s time to know more about is deceleration negative.

Why is the term negative acceleration used instead of deceleration?

The word negative acceleration is used sometimes to refer to deceleration because of its nature.

To know the value of deceleration applied on a body, we plot it on the negative coordinates of the V-T graph. Since we are plotting it on the negative side, even the values obtained will be negative. It also occurs due to the sudden reduction in the speed of the moving body. It is why the term negative acceleration is used instead of deceleration.

It is time to know about the fundamental differences between negative acceleration and deceleration.

Negative acceleration vs deceleration

The primary differences between negative acceleration vs deceleration are below.

  • Deceleration acting on a body is in the direction that is precisely opposite the direction in which the velocity and initial acceleration occur. It even decreases the amount of speed of the body.
  • The negative acceleration is just plotted on the negative side of the XY coordinate system of the V-T graph.

Let us know some examples of is deceleration negative.

Examples of Deceleration or negative acceleration

We find many examples of deceleration being negative around us in daily life since there are many motion changes.

While riding a vehicle, when we suddenly apply the brake, the velocity or speed decreases steadily; if the velocity reduces, then eventually the acceleration of the vehicle reduces and becomes negative, leading to deceleration. Here we must note that the initial velocity will be more than the final velocity of the vehicle.

is deceleration negative
Image Credit: Pixabay free images

Another important example is when you throw any object into the air; it moves up to a certain height then comes towards you. We can find deceleration coming into play due to gravitational force. Here the acceleration acting will be negative. When a skateboarder slows down, the acceleration becomes negative.

is deceleration negative
Image Credit: Pixabay free images

In a cricket match, after hitting a ball, the batsmen on the crease move forward to run, and suddenly he observes the ball coming back towards the wicketkeeper and moving back slowly towards his crease. Here it is noticeable that the speed at which he wanted to rush forward was more than he wanted to come back because he was almost near his position.

is deceleration negative
Image Credit: Pixabay free images

Now it’s time to study the formula used to measure deceleration.

Formula to measure deceleration

We have the formula to find the value of acceleration acting on a body. Similarly, we have one to know the deceleration value.

Deceleration consists of the beginning and final speed or velocity of a body.

Deceleration(a) = VF – VI / T

Deceleration(a) = (VF – VI)/ T

It can also be given by one of the prominent equations of motion

                                          V = u – at

In the above formulas,

I, U= velocity at the beginning

F = velocity at the end of motion

a = The value of deceleration

T = Required time of the body

The SI unit used to measure deceleration is the same as that of acceleration m/s2.

How to measure deceleration on a V-T graph?

On a V-T graph, deceleration is usually measured by a falling straight line in the negative coordinate.

  • We know that acceleration is denoted by the straight line obtained by plotting values on the V-T graph. Similarly, the deceleration can be plotted on a negative coordinate; the nature of the graph, there will be an inverted straight line that shows the reduction in speed of the particle.
  • The slope taken will be considered equal to the deceleration value.
is deceleration negative

Now let us solve some problems related to deceleration.

Problems based on deceleration

The given below are some fundamental problems to study in detail about is Deceleration negative.

Problem 1

From the graph below, identify the negative acceleration or deceleration line?

Solution: Line E has deceleration since it is plotted in a negative coordinate and has a falling line.

is deceleration negative

So, these are some basic aspects that must know regarding is Deceleration negative.

Frequently Asked Questions on Deceleration | FAQs

When can we take acceleration as negative?

We can consider acceleration to be negative when the body travels in the opposite motion path.

Acceleration is generally known as the state of the body that is motion changes its velocity considering external conditions. This acceleration can be considered negative when the particle travels in the opposite/other direction of the previous acceleration.

What do you mean by negative acceleration?

Negative acceleration is generally termed deceleration.

  • The name retardation sometimes knows the term deceleration. It states precisely the opposite meaning to the definition of acceleration in terms of direction.
  • In deceleration, the body’s velocity that is in motion decreases gradually.
  • It occurs when will project the total resultant force of the body in the direction opposite to its motion.

Does both negative acceleration and deceleration mean the same?

In some extremes, both negative acceleration and deceleration have mean same.

We know that deceleration in motion decreases the speed or velocity of body and is in the opposite path of motion. In contrast, negative acceleration is a kind of acceleration that acts in the negative or opposite direction of a specific coordinate system.

Can the quantity acceleration be positive or negative?

Both positive and negative acceleration is possible as it depends on the conditions of the direction of the route the object is traveling.

  • In general, the path of motion directs how acceleration on a body occurs. It is just a value of the derivative of velocity concerning the body’s motion.
  • If this acceleration is added mathematically to the velocity/speed of the body, then we can consider that acceleration is positive.
  • If the same acceleration is subtracted from the present velocity /speed of the particle, then can term that acceleration is negative.

What is considered in physics when acceleration is negative?

We have considered the two criteria, velocity and acceleration, to know about negative acceleration in detail.

  • In physical sciences, if the acceleration is negative, then it is known by a particular term called negative acceleration or sometimes a deceleration.
  • Suppose the body’s velocity is in forwarding motion and is positive and the acceleration acting on it is in the precisely opposite direction of velocity. In that case, it is negative acceleration that reduces the fastness of the body.
  • If the body’s velocity is in backward motion and is negative and the acceleration acting on it is in the opposite direction of velocity, it is negative acceleration.
  • Here the fastness of the body increases since even the velocity is acting in the same direction.

How can you find acceleration and deceleration on a velocity-time graph?

Now we know that deceleration has the opposite meaning of acceleration.

  • It can be calculated in a similar method using a V-T graph but with a necessary condition that must take the slope in the negative coordination. After all the process of plotting and taking a slope, you can get the value of deceleration.
  • Even one can use the starting and final velocity as we calculate acceleration by adding a minus sign to it, you can get the value of deceleration.

Can negative acceleration always be considered as deceleration?

Deceleration acting on a body or particle usually decreases its velocity or speed.

  • In general, both these terms are measured on a negative coordinate of the V-T graph.
  • We can consider both deceleration ad negative acceleration to be similar only in certain conditions of the direction of the route under which the body travels. Both the terms mean the same: it acts in the opposite path to the direction in which the body’s velocity occurs.

How can you consider the velocity to be negative?

We have to consider the direction of the route in which the particle moves to find the value of velocity.

We can consider a velocity positive or negative depending on the direction of coordinates in which the body is traveling. The velocity will be positive if it travels in a positive X direction and negative if the body moves in a negative X direction.

What is the method to calculate the average deceleration of a body?

To know the average deceleration rate of a body, we can use the following formula,

Consider the starting and final velocities and square both terms and divide the obtained equation by distance multiplied by two. Now the obtained equation will be the formula to find the average deceleration.

A = VF – VI

A = (VF)2 – (VI)2

A = (VF)2 – (VI)2 /2

Raghavi Acharya

I am Raghavi Acharya, I have completed my post-graduation in physics with a specialization in the field of condensed matter physics. Having a very good understanding in Latex, gnu-plot and octave. I have always considered Physics to be a captivating area of study and I enjoy exploring the various fields of this subject. In my free time, I engage myself in digital art. My articles are aimed towards delivering the concepts of physics in a very simplified manner to the readers. Let’s connect through - LinkedIn: https://www.linkedin.com/in/raghavi-c-s-260a801b1 EMAIL ID: raghavics6@gmail.com

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