Motion in Physics Velocity part2

Motion in Physics Velocity part2 continues..

When is velocity said to have change

Velocity is a vector quantity. So, velocity has a magnitude as well as a direction. The magnitude of velocity is equal to the speed of the body. If either of the two, i.e., either speed or direction changes, velocity is said to have changed. Thus, the velocity of a body change due to a change in its speed, its direction, or both.

    Let us consider a car travelling (towards east) at a constant speed of 10 m/s. Then, it has a constant velocity in that direction. When the takes a turn, its velocity changes although its speed remains constant. When the car is at right angles to its original direction, the its velocity (towards east) becomes zero, the speed remaining constant. When the car is travelling in the direction just opposite to the original direction, it has a negative velocity. So, the velocity of a moving object changes due to a change in its direction.

What is meant by uniform velocity (or constant velocity)

Uniform (or constant) velocity is defined as,

        “when a body travels in a straight line (in a particular direction) and covers equal distances in equal intervals of time, it is said to have uniform velocity.”

      Thus, a body is said to have uniform (or constant) velocity if it covers equal distances in equal intervals of time in a particular direction.

    Thus, a body travelling with a constant speed along a straight line in a particular direction has uniform velocity.

What is meant by non-uniform velocity

   Non-uniform velocity is defined as,

     “A body is said to have non-uniform velocity when it covers unequal distances in equal time intervals in a particular direction, or when it covers equal distances in equal intervals of time, but changes its direction during the motion.”

A car turning a corner at constant speed has non-uniform velocity.

What is meant by average velocity of a body moving in a particular direction

If the velocity of a body in a particular direction changes continuously at a uniform rate, then the arithmetic mean of the initial and final velocities over a given period of time, is called the average velocity in that direction. So, Average velocity in a particular direction,

         v_av =  (Initial velocity + Final velocity)/ 2

If, u is the initial velocity, and v is the final velocity in a particular direction, then

Average velocity in a particular direction, v_av = (u + v)/2

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SmartiesGeeks (Sashi kant)