Differentiate between speed and velocity.

Speed is a scalar quantity representing the rate of motion, while velocity is a vector quantity that includes both speed and direction.

Speed, in physics, is defined as the distance travelled per unit of time. It is a scalar quantity, meaning it only has magnitude and no direction. It is measured in units such as metres per second (m/s), kilometres per hour (km/h), or miles per hour (mph). Speed tells us how fast an object is moving, but it does not tell us in which direction the object is moving. For example, if a car is moving at 60 km/h, that is its speed.

On the other hand, velocity is a vector quantity. This means it has both magnitude (speed) and direction. It is defined as the rate of change of displacement, which is the shortest distance from the initial to the final position of an object. Velocity tells us how fast an object is moving and in which direction it is moving. For instance, if a car is moving at 60 km/h to the north, that is its velocity.

The difference between speed and velocity is crucial in physics. For example, if a car is moving in a circular path at a constant speed, its velocity is continuously changing because its direction is continuously changing. Even though the speed remains constant, the car is accelerating because its velocity is changing. This is an example of circular motion, a key concept in physics.

In summary, while speed and velocity might seem similar at first glance, they are distinctly different concepts in physics. Speed is a scalar quantity that only considers how fast an object is moving, while velocity is a vector quantity that considers both the speed and direction of an object's movement. Understanding the difference between these two concepts is fundamental to understanding motion in physics.