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What is the difference between speed,velocity & acceleration?



Definition of velocity in physics

Velocity is defined as:”The rate of displacement of a body is called its velocity.”The velocity tells us not only the speed of a body but also the direction along which the body is moving.Velocity of a body is a vector quantity.It is equal to the displacement of a body in unit time.

What is the formula for Velocity?

\Velocity=\frac { displacement\quad  }{ time } \\ \quad \quad \quad \quad V=\frac { d }{ t }

Here d is the displacement of the body moving with velocity v in time t.

Unit for velocity in physics:

SI unit of velocity is the same as speed i.e.,meter per second.

Uniform velocity

“A body has uniform velocity if it covers equal displacement in equal intervals of time however short the interval may be.”In equation( d=v t ) is the average velocity of of a body during time t .It is because the velocity of the body may be changing during the time interval t.However,in many cases the speed and direction of a body does not change .In such a case the body possesses uniform velocity.That is the velocity of a body during any interval of time has the same magnitude and direction.

Average velocity definition

“Average velocity is the total displacement covered in any direction in total interval  of time.”or ratio of total displacement to time is called average velocity.

 average velocity formula

average velocity formula

Example:average velocity example

Given data is:

average velocity example 2

Difference between speed and velocity in physics

difference between speed and velocity


Watch also video about instantaneous velocity:



Relationship between power and velocity:

It is some times,convenient to express power in terms of a constant force F acting on an object moving at constant velocity v.For example,when the propeller of a motor boat causes the water to exert a constant force F on the boat,it moves with a constant velocity V.The power delivered by the motor at any instant is given by:

relationship between power and velocity

The dot product of force and velocity is called power.


See also terminal velocity:

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