Motion in physics is a fundamental concept that describes the change an object goes through in terms of position with respect to time. It is one of the key concepts that governs our physical world, from the simplest things such as throwing an object to more complex concepts such as the movement of planets and other celestial bodies. Studying motion is crucial when taking a step into understanding the physical world. Motion is also the backbone upon which other scientific and technological advancements were made. In this article we shall explore motion in physics, its different laws, and the various types of motion that we have.
In simple terms, motion can be defined as the change in position of an object with respect to its surrounds over an amount of time. Motion can take one of two quantities, either a scaler quantity, when only magnitude is considered, or a vector quantity, when magnitude as well as direction are considered.
In the whole universe, nearly every phenomenon that we know of involves motion in some form, as such it is very important that we study and understand this concept. Understanding motion and the principles that govern it will help in science, engineering, designing efficient systems, making accurate predictions, and most important of all, solving real-world problems.
Fundamentals of motion
Position and displacement are one of the very first things you will hear when motion is mentioned. Position is the coordinate of an object or its location in a space. Displacement is the change in the position of said object from its initial to final position. Displacement is a vector quantity as it takes into account the distance travelled as well as the direction of travel.
Speed, velocity, and acceleration are another fundamental concepts. Speed is a representation of the rate at which an object covers a certain distance, making it a scalar quantity. Velocity takes into account both the speed of an object along its direction, making it a vector quantity. Acceleration is also a vector quantity that is the measure of the rate of change of velocity with respect to time. Understanding speed, velocity and acceleration will give you an insight into the dynamics of moving objects.
Equations of motion
The equations of motion describe the relationship between an object’s position, velocity, acceleration, and time. This can only be applied when acceleration is constant and motion is in a linear line. The equations of motion are versatile and can also be exchanged when gravity comes into play. These equations can be seen below:
$$
v=u+a t
$$
$$
s=u t+\frac{1}{2} a t^2
$$
$$
v^2=u^2+2 a s
$$
Where:
v = Velocity
u = Initial velocity
a = Acceleration
t = time
s = distance travelled
Laws of Motion in physics
As the story goes, Sir Isaac Newton was sitting under a tree when an apple fell on his head. It is said that this event sparked the curiosity in his mind and lead to the development of his laws of motion. Weather this story is true or not is insignificant. The fact is that Sir Isaac Newtons Laws of motion laid the foundation for classical mechanics and will reaming essential when it comes to the understanding the dynamics of objects.
Newtons first law (Law of inertia)
Newtons first law states that an object in motion tends to stay in motion, and an object at rest tends to stay at rest with linear speed and direction unless acted upon by an external force. This law is an introduction to what inertia is, which is the tendency of an object to resist change when in its state of motion.
Newtons second law (Law of force and acceleration)
The Law of force and acceleration describes the relationship between the force acting upon an object, its mass, as well as its acceleration. It states that the total force applied to an object will always be equal to the mass of the object multiplied by its acceleration. The formula for Newtons second law is given below:
$$
\vec{F}=m \vec{a}
$$
Where:
F = Force
m = mass
a = Acceleration
Newtons third law (Law of action and reaction)
The famous Newtons third law of motion states that for every action, there is an equal and opposite reaction. In other words, this can be seen as when two objects A and B exert force, the force exerted by object A on B will be equal in magnitude as well as opposite in direction to the force that will be exerted by object B on A.
Types of Motion.
Motion can also be divided into further types. From the simple linear motion to the more complex and ironic simple harmonic motion, there are various types of motion which play a part in each of their own respective fields and are equally essential to understanding motion as a whole.
Linear motion
Linear motion concerns the movement of an object in a linear or straight path. Examples of linear motion include such things as the motion of cars on a straight road or the falling of an object under the force of gravity. When considering the movement of a car on a straight road, the motion remains linear as long as no external forces like friction or wind resistance act upon it.
Circular motion
This type of motion happens when an object is moving along a circular path. This introduces the concept of centripetal force, which is responsible for keeping the object in that circular motion, always in the direction of the center of the circle. Circular motion can be found in many scientific as well as technological applications. In a particle accelerator for example, charged particles are subjected to circular motion via magnetic fields. The formula for centripetal force is given below:
Oscillatory motion
In simple terms, oscillatory motion is the back-and-forth motion around a central point repeatedly. Oscillatory motion can also be further divided into simple harmonic motion and pendulum motion. In a simple harmonic motion, the restoring force this is the cause of the motion is always proportional to the displacement from an equilibrium position. When a pendulum swings back and forth under the gravity, it is said to undergo pendulum motion. The formula for both simple harmonic motion and pendulum motion is written below:
Simple harmonic motion:
$$
\mathbf{F}=-k \mathbf{x}
$$
Where:
F = Restoring elastic force
k = Spring constant
x = Displacement
Pendulum motion:
$$
\frac{d^2 \theta}{d t^2}+\frac{g}{\ell} \sin \theta=0
$$
Where:
d = Distance
g = Magnitude of the gravitational field
l = Length of rod or cord
Theta = Angle from the vertical to the pendulum
Understanding motion, its laws, and types is crucial. From Robotics, transportation, and even sports, motion in physics is very essential to the prosperity of each field. Knowledge of these concepts will give you the fundamentals you will need in order to further your education in fields concerning motion such as mechanics, kinematics, dynamics, and thermodynamics. If you have understood the concepts above, you have just dipped into the world of motion and anything along the way will not be complicated to understand as these are the backbones upon which anything else can be built on.
Frequently asked questions (FAQs)
Q1 – What is motion definition in physics?
Motion in physics is a fundamental concept that describes the change an object goes through in terms of position with respect to time.
Q2 – What are the types of motion?
The main types of motion include linear motion, circular motion, and oscillatory motion.
Q3 – What is the study of motion in physics?
The study of motion in physics is known as kinematics.
Q4 – What are the laws of motion?
The laws of motion are three. They include Newtons first law (Law of inertia), Newtons second law (Law of force and acceleration), and Newtons third law (Law of action and reaction).
