General Kinematic Equations

Oct 13, 2025 by wbrum.org 124 views

Introduction

In physics, the general kinematic equations of motion are used to describe the motion of an object under the influence of a constant acceleration. These equations are widely used to solve problems involving horizontal and vertical motion. However, for horizontal displacement, the equations can be simplified significantly. In this article, we will derive the simplified equation for horizontal displacement and explain how it is obtained from the general kinematic equations.

General Kinematic Equations

The general kinematic equations of motion are given by:

Equation of Motion for Position: $x = x_0 + v_0t + \frac{1}{2}at^2$
Equation of Motion for Velocity: $v = v_0 + at$
Equation of Motion for Acceleration: $a = \frac{v - v_0}{t}$

where $x$ is the final position, $x_0$ is the initial position, $v_0$ is the initial velocity, $v$ is the final velocity, $a$ is the acceleration, and $t$ is the time.

Simplification for Horizontal Displacement

For horizontal displacement, the acceleration due to gravity is zero, and the motion is not affected by the vertical component of the acceleration. Therefore, the general kinematic equations can be simplified by setting the acceleration to zero.

Simplified Equation for Horizontal Displacement

The simplified equation for horizontal displacement is given by:

$x = x_0 + v_0t$

This equation can be obtained by setting the acceleration to zero in the general equation of motion for position.

Derivation of the Simplified Equation

To derive the simplified equation, we start with the general equation of motion for position:

$x = x_0 + v_0t + \frac{1}{2}at^2$

Since the acceleration is zero for horizontal displacement, we can set $a = 0$ :

$x = x_0 + v_0t + \frac{1}{2}(0)t^2$

Simplifying the equation, we get:

$x = x_0 + v_0t$

This is the simplified equation for horizontal displacement.

Explanation of the Simplification

The simplification of the general kinematic equations for horizontal displacement is due to the fact that the acceleration due to gravity is zero in this case. As a result, the vertical component of the acceleration does not affect the motion, and the equation can be simplified by setting the acceleration to zero.

Conclusion

In conclusion, the simplified equation for horizontal displacement is given by $x = x_0 + v_0t$ . This equation can be obtained by setting the acceleration to zero in the general equation of motion for position. The simplification of the general kinematic equations for horizontal displacement is due to the fact that the acceleration due to gravity is zero in this case.

Applications of the Simplified Equation

The simplified equation for horizontal displacement has numerous applications in physics and engineering. It is used to solve problems involving horizontal motion, such as the motion of a projectile, the motion of a car, and the motion of a particle under the influence of a constant acceleration.

Example Problems

A car is traveling at a speed of 20 m/s and is accelerated at a rate of 2 m/s^2. How far will it travel in 5 seconds?
A particle is moving horizontally with an initial velocity of 10 m/s and is accelerated at a rate of 1 m/s^2. How far will it travel in 3 seconds?

Solution to Example Problems

To solve this problem, we can use the simplified equation for horizontal displacement:

$x = x_0 + v_0t$

We are given the initial velocity $v_0 = 20$ m/s, the acceleration $a = 2$ m/s^2, and the time $t = 5$ s. Plugging in these values, we get:

$x = 0 + 20(5) = 100$ m

Therefore, the car will travel 100 meters in 5 seconds.

To solve this problem, we can use the simplified equation for horizontal displacement:

$x = x_0 + v_0t$

We are given the initial velocity $v_0 = 10$ m/s, the acceleration $a = 1$ m/s^2, and the time $t = 3$ s. Plugging in these values, we get:

$x = 0 + 10(3) = 30$ m

Therefore, the particle will travel 30 meters in 3 seconds.

Conclusion

Q: What is the simplified equation for horizontal displacement?

A: The simplified equation for horizontal displacement is given by $x = x_0 + v_0t$ . This equation can be obtained by setting the acceleration to zero in the general equation of motion for position.

Q: Why is the acceleration zero for horizontal displacement?

A: The acceleration due to gravity is zero for horizontal displacement. As a result, the vertical component of the acceleration does not affect the motion, and the equation can be simplified by setting the acceleration to zero.

Q: What are the assumptions made in deriving the simplified equation?

A: The assumptions made in deriving the simplified equation are:

The acceleration due to gravity is zero.
The motion is horizontal.
The acceleration is constant.

Q: Can the simplified equation be used for vertical displacement?

A: No, the simplified equation cannot be used for vertical displacement. The simplified equation is only applicable for horizontal displacement.

Q: What are the applications of the simplified equation?

A: The simplified equation has numerous applications in physics and engineering, including:

Solving problems involving horizontal motion.
Calculating the distance traveled by an object under the influence of a constant acceleration.
Determining the time it takes for an object to travel a certain distance under the influence of a constant acceleration.

Q: Can the simplified equation be used to solve problems involving non-constant acceleration?

A: No, the simplified equation is only applicable for constant acceleration. If the acceleration is non-constant, the general kinematic equations must be used.

Q: What is the difference between the simplified equation and the general kinematic equations?

A: The simplified equation is a special case of the general kinematic equations, where the acceleration is zero. The general kinematic equations are more general and can be used to solve problems involving non-zero acceleration.

Q: Can the simplified equation be used to solve problems involving multiple objects?

A: No, the simplified equation is only applicable for a single object. If multiple objects are involved, the general kinematic equations must be used.

Q: What are the limitations of the simplified equation?

A: The limitations of the simplified equation are:

It is only applicable for horizontal displacement.
It assumes a constant acceleration.
It is not applicable for non-constant acceleration.

Q: Can the simplified equation be used to solve problems involving relativistic motion?

A: No, the simplified equation is only applicable for non-relativistic motion. If relativistic motion is involved, the general kinematic equations must be used.

Conclusion

In conclusion, the simplified equation for horizontal displacement is given by $x = x_0 + v_0t$ . This equation can be obtained by setting the acceleration to zero in the general equation of motion for position. The simplified equation has numerous applications in physics and engineering and can be used to solve problems involving horizontal motion. However, it has limitations and is not applicable for non-constant acceleration, non-horizontal motion, or relativistic motion.