## What is speed ?

**In physics,** speed is a measure of how quickly an object moves. It is defined as the distance traveled per unit of time. Speed is a scalar quantity, which means it only has magnitude and no direction.

Mathematically, speed is calculated as:

## Formula

**Speed = Distance / Time**

where the distance is the total path length covered by an object, and time is the duration it takes to cover that distance.
**The SI unit of speed is meters per second (m/s), but other common units include kilometers per hour (km/h) and miles per hour (mph).**
It's important to note that speed does not indicate the direction of motion.

**For example,** " if a car is moving at 60 km/h, it tells us the magnitude of its speed but not the direction in which it is traveling. To describe both speed and direction, we need to consider velocity, which is a vector quantity ".

## Speed Unit

**Meters per second (m/s):**This is the SI (International System of Units) unit of speed. It represents the distance traveled in meters divided by the time taken in seconds.

**Kilometers per hour (km/h):**This unit is commonly used in everyday situations, such as measuring the speed of vehicles. It represents the distance traveled in kilometers divided by the time taken in hours.

**Miles per hour (mph):**This unit is primarily used in countries that follow the Imperial system of measurement, such as the United States and the United Kingdom. It represents the distance traveled in miles divided by the time taken in hours.

**Knots (kn):**This unit is used primarily in maritime and aviation contexts to measure the speed of ships and aircraft. One knot is equal to one nautical mile per hour, where a nautical mile is a unit of measurement based on the circumference of the Earth.

## Types of Speed

**Instantaneous speed****Uniform speed****Average speed****Variable speed**

**Uniform Speed:**When an object covers equal distances in equal time intervals, it is said to have uniform speed. In other words, the object maintains a constant speed without any changes along its path.

**Variable Speed:**An object is said to have variable speed when it covers different distances in equal time intervals. This means that the object's speed changes over time, either increasing or decreasing.

**Average Speed**: Average speed is determined by dividing the total distance traveled by an object by the total time taken. It provides an overall measure of how fast the object is moving over a given distance. Average speed considers the entire duration of the motion, regardless of whether the speed is uniform or variable.

**Instantaneous Speed:**Instantaneous speed refers to the speed of an object at a specific instant or moment in time. It represents the object's speed at a particular point on its path. Instantaneous speed is often calculated by finding the limit of the average speed as the time interval approaches zero.

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