Talha's Physics Academy
Unit No. 2 Kinematics - Velocity & Acceleration
Q. Define Velocity, its formula and unit.
Definition
Displacement covered by an object in a unit time is called velocity.
Formula
Velocity = $\frac{\text{Displacement}}{\text{Time}}$ ⇒ $v = \frac{d}{t}$
Where:
• “v” is the velocity of the object
• “d” is the change in displacement
• “t” is the time taken by it
• “v” is the velocity of the object
• “d” is the change in displacement
• “t” is the time taken by it
Unit
Its S.I. unit is meter per second (m/s).
Nature
It is a vector quantity.
Q. Define Acceleration, its formula and unit.
Definition
Rate of change of velocity of an object with respect to time is called acceleration.
Formula
Acceleration = $\frac{\text{Change in Velocity}}{\text{Time}}$ ⇒ $a = \frac{\Delta v}{t}$
Where:
• “a” is the acceleration of the object
• “$\Delta v$” is the change in velocity
• “t” is the time taken by it
• “a” is the acceleration of the object
• “$\Delta v$” is the change in velocity
• “t” is the time taken by it
If $v_i$ is the initial velocity of a body and $v_f$ is the final velocity of that body which is changed in time $t$, then we can also write as:
$a = \frac{v_f - v_i}{t}$
Unit
Its S.I. unit is meter per second squared ($\text{m/s}^2$).
Nature
It is a vector quantity.
Note & Analysis
-
Positive Acceleration: The increase in velocity gives rise to positive acceleration. It means the acceleration is in the direction of velocity.
Figure: Positive Acceleration (Acceleration is in the same direction as velocity)
-
Negative Acceleration (Deceleration / Retardation): Acceleration due to decrease in velocity is negative and is called deceleration or retardation. The direction of deceleration is opposite to that of velocity.
Figure: Deceleration / Retardation (Acceleration is opposite to the direction of velocity)
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