Kinematics of Straight Motion: Understanding the Definition and Formulas


Kinematics of linear motion is a branch of classical mechanics which deals with the motion of objects.

In kinematics you will find many terms of motion, distance, rate, displacement, and velocity.

Kinematics is in physics. One of the discussions of this science is straight motion which is already familiar.

Also Read: Centripetal and Centrifugal Forces in Circular Motion Physics

Definition of Kinematics of Straight Motion and its Formulas

In simple terms, motion means the displacement of distance. While the distance is the length of the path that the object can travel regardless of direction.

On the other hand, displacement has a meaning as the length of the path that takes into account the direction or position of an object, both at the beginning and at the end.

According to the trajectory, motion is divided into several types, namely curved or parabolic motion, circular motion, and straight motion. In physics, there is a discussion about the kinematics of objects moving in a straight line.

In general, kinematics is a branch of science from classical mechanics. The discussion of kinematics is related to the motion of objects.

However, kinematics does not pay attention to the cause of the motion of the object itself. However, kinematics is still concerned with distance, motion, rate, displacement, and velocity.

Kinematics which discusses motion in a straight line is a branch of science that deals with how objects move in a straight line but the forces that cause them cannot be noticed.

There are several formulas for this type of kinematics. Here’s the explanation.

Also Read: Dynamics of Rotational Motion: Moments of Force, Angular Moments, and Kinetic Energy

Average Speed ​​and Speed

While the average speed is the ratio between the travel time an object has with its displacement. Then there is a direction and magnitude in the velocity so that it is included in the category of vector quantities.

The formula for the average speed is:

Average speed = Change of an object / travel time

V = Delta x / Delta t

V = (x2-x1) / (t2-t1)

In addition to speed, there is also the average speed which is the distance or length of the path per unit time that an object travels. The kinematics formula for straight motion with average speed is:

Average speed = Distance traveled / time traveled

V = x / t

Uniform Motion (GLB)

GLB is the motion of an object that has a constant speed in a straight line without acceleration. Meanwhile, the formula for GLB is:

V = s/t


  • v = Speed ​​(m/s)
  • s = Displacement (m)
  • t = Time(s)

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Uniform Straight Motion (GLBB)

In addition to the formula regarding kinematics with the motion of a straight object above, there is also the notion of uniformly changing straight motion which is the straight motion of an object.

An object will change its velocity because there will be a constant acceleration. The meaning of the constant acceleration is the acceleration of the same time.

Then, the GLBB formula is:

s = V0 xt ± xax t²

Vt² = V0² + 2 x acceleration x distance

Vt = V0 ± axt


  • V0 is Initial Velocity (m/s)
  • While Vt is the final velocity (m/s)
  • t = Time(s)
  • s = Distance (m)
  • While a is Acceleration (m/s²)

Well, that is a complete understanding with the formulas of straight motion kinematics in physics that you can understand well.


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