Skip to content

What is Acceleration in Physics?

What is Acceleration in Physics?

Acceleration in physics is the rate of change of velocity with respect to time. It is a vector quantity, meaning it has both magnitude and direction. Acceleration occurs when an object speeds up, slows down, or changes direction, and it is measured in units such as meters per second squared (m/s²) in the International System of Units (SI).

Additionally, acceleration refers to the rate at which an object’s velocity changes over a specific period of time. In simpler terms, it measures how quickly an object’s speed increases or decreases. Acceleration can occur in various directions. These directions include positive (speeding up), negative (slowing down), or even sideways (change in direction).

What is Acceleration in Physics
What is Acceleration in Physics

Understanding Acceleration

Therefore, in physics, one of the key concepts which are very important is acceleration. In this comprehensive article, I will explain the concepts of acceleration by looking at its definition, formula, units of measurement, calculations, and practical applications. After reading the article, you will have a thorough understanding of this fundamental concept in physics.

Acceleration is a fundamental concept in physics. This is because it describes how an object’s velocity changes over time. It represents the rate at which an object speeds up or slows down, taking into account both the magnitude and direction of the change in velocity. When an object undergoes uniform acceleration, its velocity changes by the same amount in equal time intervals. We will later explain the uniform acceleration in this article.

Formula for Acceleration

Mathematically, we can calculate acceleration (a) by dividing the change in velocity (∆v) by the change in time (∆t). Therefore, the formula or equation that can help us to find or calculate acceleration is a = ∆v / ∆t or a = (v – u) / t.

We can write the above acceleration formula as follows:

a = ∆v / ∆t

The formula for acceleration is derived from the basic principles of physics. It can be expressed as:

a = (v – u) / t

We can rearrange the above formula for acceleration to obtain one of the equations of motion, which is v = u +at


  • a is the symbol for acceleration,
  • v represents the final velocity,
  • u is the initial velocity, and
  • t represents the time taken for the change in velocity.
  • ∆v is the change in velocity = v – u
  • ∆t is the time it takes the event to occur

Even though we will talk about it later, it is important to know that the SI unit for acceleration is meters per second squared (m/s²). This unit indicates the change in velocity per second (for every second). When an object’s acceleration is positive, it means the object is speeding up. However, when the acceleration is negative, it shows that the object is slowing down (coming to a halt).

When we look at the kinematic equations, we will see that they describe the motion of objects under constant acceleration. Thus, they involve variables such as displacement, initial velocity, final velocity, acceleration, and time. One of these equations, which involves acceleration, is:

final velocity (v)² = initial velocity (u)² + 2 × acceleration (a) × displacement (s)

Which can be written as v2 = u2 + 2as

Another one of the kinematic equations that involve acceleration is s = ut + (1/2)at2

Units of Measurement

We can measure acceleration by using various units. This depends on the context and the system of measurement employed. Apart from the SI unit (m/s²), other commonly used units include centimetres per second squared (cm/s²), kilometres per hour squared (km/h²), and even gravitational units, such as “g” or the acceleration due to gravity on Earth’s surface (9.8 m/s²).

Acceleration is typically measured in meters per second squared (m/s²) in the International System of Units (SI). Additionally, this unit shows the change in velocity (meters per second) per unit of time (seconds). Other common units that help us to express acceleration include centimetres per second squared (cm/s²) and kilometres per hour squared (km/h²).

Types of Acceleration

Acceleration can occur in various forms depending on the circumstances. Therefore, we will now explore a few common types of acceleration:

1. Uniform Acceleration

Uniform acceleration refers to a situation where an object’s velocity changes at a constant rate. In other words, the object experiences the same amount of change in velocity during each equal time interval. An example of uniform acceleration is an object falling freely near the surface of the Earth due to gravity.

2. Deceleration

Negative acceleration, also known as deceleration or retardation. Deceleration describes the scenario when an object’s velocity decreases over time. Therefore, it signifies a change in velocity in the opposite direction to the object’s initial motion. Deceleration plays a crucial role in concepts such as braking in vehicles or projectiles slowing down due to air resistance.

3. Instantaneous Acceleration

Instantaneous acceleration refers to the acceleration of an object at a specific instant in time. It represents the acceleration experienced by the object at a particular moment and can be determined by analyzing the object’s velocity-time graph.

4. Tangential Acceleration

Tangential acceleration refers to the change in an object’s tangential velocity as it moves along a curved path. This type of acceleration is directed tangentially to the object’s circular path. Thus, we can give an excellent example of tangential acceleration by observing a race car navigating a circular track.

Positive and Negative Acceleration

Acceleration can be either positive or negative. This depends on the direction of the change in velocity. Positive acceleration occurs when an object speeds up. On the other hand, negative acceleration (also known as deceleration or retardation) occurs when an object slows down. Therefore, we can see that the sign of acceleration indicates whether the object is gaining or losing velocity.

Acceleration in One-Dimensional Motion

In the context of one-dimensional motion, where an object moves along a straight line, acceleration can be either uniform or non-uniform. Uniform acceleration occurs when the object’s velocity changes by equal amounts in equal time intervals. Therefore, we can see that the issue of uniform acceleration commonly arises when a constant force is applied to an object. On the other hand, non-uniform acceleration refers to changes in velocity that are not equal over equal time intervals. Thus, this situation typically arises when varying forces act on an object.

Acceleration and Graphical Representations

Graphs provide valuable insights into the relationship between acceleration, velocity, and time. Velocity-time graphs, also known as v-t graphs, depict how an object’s velocity changes over time. Additionally, the slope of the v-t graph represents the object’s acceleration. A steeper slope indicates a higher acceleration, while a flat line indicates no acceleration (i.e., constant velocity).

It is important to know that velocity is on the y-axis (vertical plane) of the graph, while time is on the x-axis (horizontal plane) of the graph. We all know that to calculate the gradient or slope of a graph, we will have to use the formula that says s = (y2 – y1) / (x2 – x1).

But since we are dealing with acceleration, velocity and time. We will use a = s, v – u = y2 – y1, and finally t = (x2 – x1). When we substitute these values into the formula for slope, we will end up with:

a = (v-u) / t [which is the formula for acceleration].

How to Calculate Acceleration in Physics

To calculate acceleration, we need two important pieces of information: the change in velocity and the time it takes for that change to occur. The formula for acceleration is:

acceleration (a) = change in velocity (Δv) / time (Δt)

Assuming we have a velocity of 30 m/s and time of 2 seconds. We can easily calculate the acceleration by saying that:

a = v / t = 30 / 2 = 15 m/s²

Understanding the Relationship between Acceleration, Velocity, and Displacement

Acceleration, velocity, and distance are interconnected concepts that play a crucial role in understanding the motion of objects. Acceleration affects an object’s velocity. However, when we look at the velocity, we will see that it determines an object’s displacement or change in position over time.

When an object experiences a constant acceleration, its velocity changes at a consistent rate. In such cases, the relationship between acceleration (a), initial velocity (u), final velocity (v), and displacement (s) can be defined by the following equation:

v = u + at

Additionally, the displacement of an object can be determined using the equation:

s = ut + (1/2)at²

Note: In some cases, the symbol for displacement is d

Acceleration and Newton’s Laws of Motion

Acceleration is closely related to Newton’s laws of motion. According to Newton’s second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This relationship can be mathematically expressed as:

F = m × a


  • F represents the net force acting on the object,
  • m represents the mass of the object, and
  • a represents the acceleration experienced by the object.

Newton’s laws of motion provide a fundamental framework for understanding the behaviour of objects under the influence of forces, including acceleration.

Practical Applications of Acceleration in Physics

Acceleration has numerous practical applications across various fields, which include physics, engineering, transportation, and sports. We will now list and explain them one by one:

1. Motion Analysis in Sports

Acceleration is a key factor in sports that involve running, sprinting, or any form of quick movement. Athletes strive to optimize their acceleration abilities to help them acquire a competitive spirit. It can be any sport, whether it’s on the track, football field, or any other sporting arena.

It helps athletes in analyzing and improving their athletic performance. When we look at sports such as sprinting, swimming, and cycling, athletes strive to maximize their acceleration to achieve faster times. By studying an athlete’s acceleration patterns, trainers and coaches can identify areas for improvement and design training programs to enhance speed and performance.

2. Automotive Safety Systems

Acceleration is also very important in the automotive world. It is often measured in terms of 0 to 60 mph or 0 to 100 km/h times. These acceleration values provide insights into a vehicle’s performance and speed capabilities.

Therefore, we can see that it is a key parameter in automotive safety systems. These systems include anti-lock braking systems (ABS) and electronic stability control (ESC). These systems utilize acceleration sensors to monitor the rate of change of a vehicle’s velocity. By detecting sudden changes in acceleration, these safety systems can intervene to prevent skidding, loss of control, and potential accidents.

3. Space Exploration

When it comes to space missions, acceleration is critical in launching rockets and spacecraft into orbit. The precise calculations of acceleration are crucial in achieving the desired trajectory and ensuring successful missions. Acceleration is important in space exploration. This is because spacecraft undergo significant changes in velocity to reach their intended destinations.

Rockets and spacecraft rely on powerful engines to generate the necessary acceleration to overcome Earth’s gravity and achieve escape velocity. Once in space, spacecraft use controlled acceleration to manoeuvre, change orbits, and rendezvous with other celestial bodies. Accurate calculations of acceleration are essential for successful space missions and satellite deployments.

4. Physics Experiments

Acceleration is a fundamental parameter in physics experiments. Researchers often study the effects of acceleration on various objects to understand the underlying principles of motion. For example, experiments involving falling objects or pendulums can provide valuable insights into gravitational acceleration and the behaviour of systems under different forces.

5. Engineering and Construction

We consider acceleration in the design and construction of structures like bridges and skyscrapers. Engineers analyze the acceleration forces acting on these structures to ensure their stability and safety, especially in regions prone to earthquakes or strong winds. By understanding how acceleration affects the integrity of buildings, engineers can implement measures to enhance structural resilience.

Acceleration is a fundamental concept in physics and engineering. It forms the basis for understanding motion, forces, and energy. Engineers rely on acceleration calculations when designing structures, vehicles, and machinery to ensure their safety and efficiency.

6. Transportation

In the field of transportation, acceleration helps us in designing efficient vehicles. Therefore, it helps engineers to optimize the acceleration and deceleration rates of cars, trains, and aeroplanes, resulting in smoother rides and improved fuel efficiency.

7. Roller Coasters and Amusement Parks

The thrill of roller coasters and amusement park rides is often attributed to the exhilarating accelerations experienced by riders. Engineers meticulously design these attractions to provide varying acceleration forces, ensuring an exciting and safe experience for thrill-seekers.


Acceleration is a fundamental concept in physics that describes the rate of change of an object’s velocity over time. It plays a vital role in understanding the behaviour of objects under the influence of forces. By studying acceleration, we can analyze motion, calculate forces, and predict the outcomes of various physical phenomena.

Acceleration in physics refers to how quickly an object’s speed changes over time. It’s a measure of how much an object is speeding up or slowing down. Imagine a car going from a standstill to moving – the process of gaining speed involves acceleration. Similarly, when a car comes to a stop, there’s deceleration or negative acceleration.

Acceleration is a vector quantity, meaning it has both a magnitude (how much) and a direction. If you’re driving in a straight line and press the gas pedal, you’re accelerating in the direction you’re moving. If you hit the brakes, you’re still accelerating, but now in the opposite direction.

The standard unit for acceleration in the International System of Units (SI) is meters per second squared (m/s²). If an object’s acceleration is 2 m/s², it means its speed is increasing by 2 meters per second every second.

In summary, acceleration in physics describes changes in an object’s speed, including both speeding up and slowing down, and it’s measured in units like meters per second squared.

You may also like to read:

A motorist travelling with a constant speed of 15 m/s