WHAT IS VELOCITY ? EXPLAIN WITH EXAMPLE.

The time rate of change of displacement of a body is called velocity. Its direction is along the direction of displacement.

What is Average Velocity?

The ratio of the total displacement to the total time taken to cover this displacement is called as average velocity.

If ( Delta vector d ) is the displacement of body in time ( Delta t )  then average velocity is

vector v  = Delta vector d / Delta t

Velocity is a vector quantity in physics that describes the rate at which an object changes its position. It includes both speed (a scalar quantity) and direction. Velocity is often confused with speed, but while speed only tells you how fast something is moving, velocity tells you both how fast and in what direction.

Limitation of average velocity:

Average velocity does not tell us that the motion is steady or variable and the path is straight or curved.

If a squash ball comes back to its starting point after bouncing of the wall several times, its total displacement is zero and also its average velocity is zero.

Average Velocity Key Points

• Magnitude: This is the speed component of velocity, showing how fast the object is moving.

• Direction: This indicates the direction in which the object is moving.

• SI Unit: The standard unit of velocity is meters per second (m/s).

Velocity SI Unit and Direction:

Sl unit of velocity is m/sec (i.e. ms¹). Its dimensions are [LT] It is a vector quantity and its direction is also the direction of displacement.

Average Velocity Formula:

$\text{Velocity}=\frac{\text{<span style="font-size: medium;">Displacement </span>}}{\text{<span style="font-size: medium;">Time</span>}}$

Velocity= Time Displacement​

• Displacement is the straight-line distance between the starting and ending points, along with the direction.
• Time is the duration over which the movement occurs.

Average Velocity Example:

Imagine a car traveling in a straight line. It moves 100 meters to the east in 10 seconds.

Speed: The speed of the car is calculated by dividing the distance traveled by the time taken. So, $\text{Speed}=\frac{100\text{ meters}}{10\text{ seconds}}=10\text{ m/s}$.

Velocity: To determine the velocity, we must consider both the magnitude and the direction of the car's movement. In this case, the car’s velocity is 10 m/s to the east.

If the car then reverses direction and moves 100 meters back to its starting point in the same amount of time (10 seconds), its velocity for this return trip would be 10 m/s to the west. The speed remains the same, but the velocity has changed due to the change in direction.

If we consider the entire journey (100 meters east, then 100 meters west), the total displacement is zero because the car ends up where it started. Thus, the average velocity over the entire journey is zero, even though the car was moving the whole time.