Slow and Fast Motion - Examples, Types, Formulae, and FAQs
Isn't it true that the faster you drive, the sooner you get to the airport? But what exactly is the quantum that determines how fast or slow an object moves? We already know that motion refers to any change in position over time. But what counts is whether or not an object is moving slowly or quickly.
Introduction
We already know that a moving object can move in three different ways: rectilinear, circular, and periodic motion. But how can we tell if the movement is slow or fast? We determine this by observing the rate at which an object moves. So, what exactly is speed? The rate of location change is denoted by the word speed, which is a widely common word for movement. Let's talk about the different levels of motion before we talk about speed.
Bullock carts, vehicles, scooters, and bicycles may have been observed moving. How can you know which is in slow motion and which is in fast motion? The answer is straightforward: you compare them and their changes in position over time. We can tell which car is travelling quicker when all of them are moving in the same direction.
The motion of an object is defined by its speed, position, direction, and acceleration. Going by the moving objects definition, an object is moving if it changes its position relative to a fixed point. Motion is a relative term and bodies that appear to be at rest could be moving. For example, a book on a table is at rest relative to the table. Still, it moves at approximately 30 kilometers per second relative to the sun (since the earth is revolving around the sun). The speed of the book is even faster when taken relative to the center of gravity. This article will highlight what is meant by slow and fast motion, but before that, let us go through a few terms and formulae that will help in understanding slow and fast motion.
Examples of Moving Objects
In real life, we can find many things moving around us, such as:
A ball which is thrown upwards
People walking around
An airplane flying in the air
An autorickshaw moving on the road
A ship sailing in the sea
Types of Motion
There are different types of motions that an object can exhibit, and they are discussed below.
Rectilinear Motion
When an object moves in a straight line, it is said to exhibit a rectilinear motion.
Periodic Motion
A repeated motion after a fixed interval of time is called a periodic motion. Few examples are the motion of the earth around the sun, a moving pendulum, etc.
Circular Motion
In a circular motion, a body follows a circular path by force applied uniformly along the radius and towards the circle's center.
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Speed of a Moving Object
All objects move at different speeds. Speed is the rate at which an object changes its position in space or covers a certain distance. It is this speed that determines the slow and fast motion of the moving object. An object in fast motion would cover a longer distance compared to an object which is moving slowly with a low speed, in the same amount of time. An object which is not moving at all has zero speed. Earlier, people would describe speed only as slow or fast. Galileo was the first person to give a formula for speed in terms of the distance covered in a certain duration of time.
The formula for speed is:
Speed = Distance/Time
Speed is a scalar quantity and has magnitude but no direction. Speed can be expressed in several units which are used to measure distance and time. Some of these units are:
Miles per hour or mi/h
Kilometers per hour or (Km/h)
Centimeters per day
Light years per century.
Amongst animals, Cheetah has the highest speed for distances under 500 meters and the maximum speed at which it can travel is close to 100 km/hour.
Velocity of a Moving Body
Velocity has a magnitude and direction; hence it is a vector quantity. It is the rate at which a body changes its position. If a person is rapidly walking one step forward and one step back, it might look like a frantic activity, but his velocity is zero. Since the motion results in zero position change (as the person is coming back to the same position), the rate at which his position changes is zero. When mentioning the velocity of any object, the direction of motion should be stated as well. Hence, if we say that the car is moving at 60 km/hr, it does not completely express its velocity. For example, 60 Km/hr East is a velocity.
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Acceleration of a Moving Body
Acceleration of any object is the change in its velocity per unit time and can be obtained by dividing the object’s change in velocity by time.
Acceleration = change in velocity/time.
Acceleration applies both to an increase as well as a decrease in speed. The brakes of a car produce retarding acceleration that results in a huge decrease in speed per second. It is termed as deceleration. Acceleration is also a vector quantity, and a change in direction also results in acceleration. The unit of acceleration has two parts; the unit of velocity and of time. For example, “10 m/s²”, i.e., 10 meters per second². You can notice that time comes twice in the unit of acceleration, the first is for speed, and the second is for the interval of time in which the velocity is changing.
Types of Speed
Uniform Speed
If an object is covering the same distance in the same time gaps, it is said to have uniform speed.
Non-uniform Speed
If an object covers unequal distances within the same time gaps, it is said to have non-uniform speed.
Average Speed
It is the total distance travelled by a moving body divided by the total time taken in travelling that distance.
Average speed = total distance travelled/total time travelled.
FAQs on Slow and Fast Motion
1. What is motion in the context of Physics?
In physics, an object is said to be in motion when it changes its position with respect to a fixed point, known as a reference point, over a period of time. For example, a moving bus changes its position relative to a bus stop, so it is considered to be in motion.
2. How do we define slow and fast motion?
We can determine if an object's motion is slow or fast by comparing the distance it covers in a specific amount of time. An object in slow motion covers less distance in a given time, while an object in fast motion covers more distance in the same amount of time.
3. Can you provide some real-world examples of slow and fast motion?
Certainly. Comparing objects helps illustrate the concept:
- Examples of Slow Motion: A tortoise walking, the movement of a snail, or the hour hand of a wall clock.
- Examples of Fast Motion: A jet plane flying, a sprinter running a 100-metre race, or a car travelling on an expressway.
4. How is the speed of an object calculated as per the CBSE Class 7 syllabus for 2025-26?
The speed of an object is a measure of how fast it is moving. It is calculated by dividing the total distance travelled by the object by the total time taken to cover that distance. The basic formula is: Speed = Total Distance Covered / Time Taken.
5. Why is motion always considered a relative concept?
Motion is considered relative because an object's state of motion depends entirely on the observer's frame of reference. For instance, a passenger sitting on a moving train is at rest with respect to other passengers inside the train. However, for a person standing on the ground outside, that same passenger is in motion. This shows that an object can be simultaneously at rest and in motion depending on the reference point.
6. What is the main difference between uniform and non-uniform motion?
The key difference lies in the constancy of an object's speed.
- In uniform motion, an object moves along a straight path and its speed remains constant. It covers equal distances in equal intervals of time.
- In non-uniform motion, the speed of the object changes over time. It covers unequal distances in equal intervals of time, such as a car moving through city traffic.
7. If two bicycles start at the same time, does the one covering more distance always have a faster speed?
Yes, provided they travel for the same amount of time. Speed is directly related to the distance covered in a given time period. If the duration of travel is identical for both bicycles, the one that has travelled a greater distance is confirmed to have a higher average speed. This is a direct application of the relationship Speed = Distance / Time.
8. What are the standard units used for measuring speed, and why is it important to be consistent?
The basic S.I. unit for measuring speed is metres per second (m/s). For practical situations involving vehicles like cars or trains, a larger and more convenient unit, kilometres per hour (km/h), is often used. Using consistent units is crucial for accurate calculations. If distance is in metres and time is in hours, you must convert them to a consistent system (like m/s or km/h) before calculating speed to avoid incorrect results.
