What are the Laws of Motion? What is Motion? It’s Types & Parameters (with PDF)

What is motion?

Defining Motion
Defining Motion

Motion is the change in position or orientation of an object over time. Everything in this universe is in constant motion, including the movements of animals and humans. Apart from that, the elementary particles of matter, also called atoms, are also in a state of continuous motion. This means that all physical processes in this universe have some motion, and that motion is either slow or fast, but always present.

Moving objects can be seen everywhere. Animal and human movements are examples of everyday movements. Even the basic particles of matter – atoms – are in constant motion. All physical processes in this universe consist of some form of movement. It can be slow or fast, but the movement is there. But when a person snores, do we say that the person is moving, or do we say that a chirping bird resting on a tree is moving? How do you define movement?

So how do you define a moving object? By comparing the new position with the original position, you can detect the movement of the object. A change in an object’s position over time is considered motion. Some things are in motion, and others, such as the Earth, appear to be stationary but are actually in motion. Just as the earth itself is in motion, anything that appears stationary on earth is actually in motion (i.e., spins and orbits). This page will help you easily identify the difference between rest and exercise, types of exercise, and give examples.

How to identify moving objects?

From the above text, it is clear that we can determine the movement of an object by comparing its new position with its original position. A change in an object’s position over time is considered motion. We find some things that are always in motion, like the earth, which seems to be stationary, is always in motion. Just as the earth itself is in motion, anything that appears stationary on earth is actually in motion (i.e., spins and orbits).

How to determine if an object is moving: Moving Parameters?

An orange falling from a tree, water running from a faucet, and a rattling window all indicate that an object is in motion. So, let’s take a look at the following key terms that help us determine motion:

  • Distance: The distance traveled by an object is defined as the total path length traveled by the object.  is a scalar quantity. Its SI unit is the meter (m).
  • Speed: Object speed indicates how fast or slow an object is moving. It is defined as the distance traveled by an object in a unit of time. Let d be the distance traveled by the object and t be the time it takes the object to travel this distance, then the speed of the object is given by S=dt. Object speed is measured in meters per second (ms–1).
  • Displacement: The shortest distance between the end and start positions of moving objects. vector size. Its SI unit is the meter (m). Suppose an object follows a curve from point A to point B. In this case, the distance moved by the object is the length of the curve, but the displacement of the object is given by the shortest length between points A and B.
  • Velocity: It is defined as the rate of change of an object’s position relative to a reference frame or displacement per unit of time. It is a vector quantity and can be measured in meters per second
  • Acceleration: It is defined as the rate of change in velocity. The object’s acceleration is given by a = (v−u)t, where u is the object’s initial velocity, v is the object’s final velocity, and t is the duration. It is a vector quantity and its SI unit is (ms–2).
Distance and Displacement
Fig.-1: Distance and Displacement

Distance & Displacement

Let’s understand the concept of Distance & Displacement.

Refer to the given Fig.-1 where a boy takes the straight rectangular path from point A to B, B to C, C to D, & D to A by covering the distances as mentioned.

So, the Distance covered by the boy:

4m + 2m + 4m + 2m = 12m and the Displacement will be 0m. Because the initial point and final point are the same.

Types of Motion

Now let’s talk about the characteristic types of motion found in objects. These are linear motion, rotary motion, oscillatory motion, and periodic motion. Each of these types is performed by dedicated mechanical means. Let’s analyze it in detail.

Linear Motion

In linear motion, an object moves from one position to another either in a curved direction or in a straight line. Given the type of direction taken by an object, linear motion is similarly classified as follows:

  • Rectilinear Motion – The path taken by the body is straight. (Figure-2)
  • Curvilinear Motion – The path taken by the body is curved. (Figure-3)
Curvilinear Motion
Fig. 3: Curvilinear Motion
Rectilinear Motion
Fig. 2: Rectilinear Motion

Examples of linear motions

One beautiful example of linear motion is a linear actuator. With linear actuators, cars, bicycles, trains, and various automobiles can be found moving in one linear direction. However, although trams and rails are perfectly circular, they are not called linear motion. You can also find linear cylinders that exhibit linear motion in pneumatic, hydraulic and electric options. Linear motion is very important in fields such as manufacturing, automation, and robotics.

Rotary Motion

Rotational motion is a type of motion in which an object undergoes circular motion. This type of motion occurs when an object rotates around its position or axis. The rotary movement became the first type of movement invented by ancient scientists. Some examples to help understand rotational motion are:

Examples of Rotary Motion
Fig. 4: Examples of Rotary Motion
Rotary Motion Examples
Fig. 5: Rotary Motion Examples

The rotation of the earth around the sun is a good example of rotational motion. Another example is the movement of the wheels and steering wheel of a car while driving. You can see that each rotates around its own axis.

The same applies to car engines. Like linear cylinders, rotary drives are today mainly used in various industries. These cylinders are available in pneumatic, electric, and hydraulic options.

Oscillatory Motion

This is the third type of movement, characterized by the movement of objects in the form of back-and-forth oscillations. In other words, oscillatory motion is described as the motion of a body around its mean position. If an object repeats its motion cycle after a while, it looks like an oscillating motion.

Oscillatory Motion
Fig. 6: Oscillatory Motion

One beautiful example of oscillatory motion is the clock pendulum. Repeat the movement after a certain time frame. In a practical sense, the pendulum has not shifted from its roll. It stands still in a single position but shows movement. Such movements that are repeated after a certain period are called oscillatory movements.

In this type of motion, the motion of the body is called vibration. This is due to the repetitive nature of the movements occurring after some time. Here are some different diagrams of oscillatory motion:

Example of Oscillatory Motion
Fig. 7: Example of Oscillatory Motion
  • When a toddler bounces back and forth on a fixed position on the swing.
  • A fan is another example of periodic motion.
  • In addition to rotary drives, both linear drives have an oscillating motion.
  • Waves Sound waves are the result of the vibration of particles.
  • Strumming a sitar or guitar string causes it to move back and forth around the center (oscillating motion).
Circular Motion
Fig. 8: Circular Motion

Circular Motion

An object in a circular orbit is called circular motion. The object’s distance from the center of the circular path remains constant.

For example, a man sitting on a Ferris wheel and the moon’s orbit around the Earth.

Laws of Motion

Sir Isaac Newton studied Galileo’s idea that objects move with constant velocity when no forces act on them and gave three basic laws that govern their motion. Newton’s laws of motion are:

Newton’s First Law of Motion

An object remains at rest or in uniform linear motion unless an applied force forces it to change its state. This law is also called the law of inertia. The term inertia refers to the tendency of an object to resist changes in its existing state of rest or motion.

Inertia: The property of matter that prevents the body from moving or changing on its own movement.

Newton’s Second Law of Motion

This law states that the rate of change of a body’s momentum is directly proportional to the imbalance force applied in the direction of the force. Let ({m}) be the mass of the moving body, (v) and (u) be the final and initial velocities, respectively, and (F) be the applied force,

F(mv–mu)/t

a=(v-u)/t
F=kma
F=ma

where k is the constant of proportionality with a value of 1 and a is the acceleration of the body.

Newton’s Third Law of Motion

This law states that every action has an equal and opposite reaction. For example, if the weight of an object (F1) exerts a force on the ground, the ground exerts the same opposing force (F2) on the object.

Equations of Motion

The three equations of motion relate to the initial velocity of the object (u), the final velocity of the object (v), the distance traveled by the object (s), the time taken (t), and the acceleration (a) is achieved by an object undergoing constantly accelerated motion.

v=u+at
s=ut+(1/2)at2
v2–u2=2as

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Atul Singla

Hi ! I 'm Atul. I am PMP certified Mechanical (Piping) Engineer with more than 17 Years of experience. Worked in the field of Plant design for various industries such as refinery, petrochemical & chemical, Fertilizer, gas Processing industries. Developed passion about Piping while working with national & international engineering consultants on diverse projects involving international clients. Developed courses on Piping Engineering to share the knowledge gained after working with many industry experts, through out these years.

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