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# Speed with Direction

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Last updated date: 15th Sep 2024
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## What are Speed and Direction?

Speed is defined as how fast an object is moving. It's expressed in metres per second (m/s). Speed is a vital constituent of kinematics in Physics. It is a scalar quantity, and it is the rate at which an object covers a specified distance. Speed doesn't have a specific direction. The speed with direction is termed velocity.

Speed is defined by its magnitude and the path at which an object is moving. The absence of an arrow over the symbol indicates that speed is a scalar quantity. It's defined as a specific distance covered per unit of time. We can easily calculate speed based on the formula:

Speed = Distance/Time

This distance is measured in metres and time is measured in seconds.

## Instantaneous Speed

Instantaneous speed is the rate at which an object moves at a given instant. An example of speed can be a car being driven 55 miles/hour, someone cooking quickly in 10 minutes, speed of a jaguar when it runs like the wind. Direction is the path on which a person or a thing is moving along that has to be taken to reach a particular place.

It also means that one is going left instead of going right. It is the information in a relative position of one point with respect to another point. North, East, South and West are the four directions often marked with N, S, S and W. East is the clockwise direction of rotation from the North.

## Speed in a Specific Direction - Velocity

The speed of an object in a specific direction is called the velocity of an object. Velocity is a vector quantity as it possesses both magnitude and direction, while speed only has magnitude but no direction. SI unit of velocity is m/s. Both velocity and speed provide us with a perspective on how fast or slow an object may be moving.

The speed in a given direction is called velocity, and it is the rate of change of displacement. Velocity is a vector quantity as it possesses both magnitude and direction, whereas speed has magnitude and no direction. So, the vector difference between the ending and starting points of a moving object is displacement. Speed is directly related to distance, whereas velocity is related to displacement.

Sometimes we have to compare where we need to know which of the two objects is moving faster than the other, it's easier if two objects are moving in the same direction and on the same path. If the said two objects move in opposite directions, it's difficult to predict the fastest moving object. In such cases, the concept of velocity clarifies the speed of the faster moving object.

Velocity is the speed in a specific direction, the rate of change of an object's position with respect to a time frame and in a specified direction. A slight differing factor emerges as if there is a change in magnitude or the direction of the velocity of the said object; it is said to be accelerating. Velocity being speed in a specific direction can be quantified as initial and final velocity.

Initial velocity means how fast an object moves when gravity applies its force on it. The final velocity is a vector quantity that measures the speed and direction of a moving object after it has achieved its highest acceleration. Constant velocity means the simplest form of movement of an object.

For example: 8 metres per second is a scalar quantity. 8 metres per second west is a vector quantity. As an object moves, a change in speed is observed that is accelerating and decelerating, so during the entire trip, a car may be moving fast or slowing down. The average speed when the car was in movement is the average of all the speedometer readings.

## The Speed of an Object in a Particular Direction

Velocity is a vital concept in kinematics and a branch of classical mechanics that explains motion in bodies. Speed in a particular direction is velocity which being a vector quantity needs both magnitude and direction, whereas the scalar absolute value of velocity is called speed.

## Interesting Fact

Robert Peary used a compass to reach the North pole, the first person to do so because compasses point in a northern direction at the geographic north pole.

## Key Features

• The speed of an object in a particular direction is called velocity.

• Speed in a particular direction is velocity, a vector quantity that needs both magnitude and direction, whereas the scalar absolute value of velocity is called speed.

• Speed is directly related to displacement, whereas velocity is related to distance.

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## FAQs on Speed with Direction

1. What is constant velocity?

An object has to have a constant speed in a constant direction to possess a constant velocity. Constant direction is a major requirement which means the object in motion has to move in a straight path/ line at a constant speed. A body cannot possess its velocity constant while the speed varies. It can be that the speed is constant and the velocity is varying. In order for the velocity to be constant, the magnitude of the velocity and the direction must not change.

2. What does displacement mean?

If an object moves from one position to another, the length of the shortest distance from the initial point to the final point of the object is known as displacement. It is the change in position of an object. Being a vector quantity, it has magnitude and direction both. It is represented by an arrow from the initial point to the final position. For example, if an object Q moves some distance, its position changes. If an object Q comes back to its original position after covering some distance, then its overall displacement will be zero.

3. What do different symbols mean in Physics?

A triangle symbol means that the value possesses direction and magnitude and is represented by an arrow that symbolises it from the initial to the final point. In Physics, various symbols are used to denote various quantities. Some are easy to note, such as "d" for distance, while some are unrelated, like "c" for the speed of light.

• Mass is denoted by ‘M’

• Time is denoted by ‘t’

• Velocity by ‘v’

• Acceleration by ‘a’

• Force by ‘F’

• Power by ‘P’

• Momentum by ‘p’ and so on and so forth.