How Velocity Affects Position: If the Change in Position dx is Related to Velocity

Velocity is a measure of how fast an object is moving in a certain direction. Position is a measure of where an object is located relative to a reference point. But how are these two quantities related? How does velocity affect position? In this article, we will explore the mathematical relationship between velocity and position, and how it can be used to describe the motion of objects in one dimension.

Velocity as the Rate of Change of Position

One way to think about velocity is as the rate of change of position. That is, how much does the position of an object change in a given amount of time? For example, if a car moves 10 meters to the right in 2 seconds, then its velocity is 5 meters per second to the right. This means that for every second that passes, the car’s position changes by 5 meters to the right.

Mathematically, we can write this relationship as:

�=Δ�Δ�v=ΔtΔx​

where �v is the velocity, Δ�Δx is the change in position (also called displacement), and Δ�Δt is the change in time. The symbol ΔΔ means “change in” or “difference between”. This equation tells us that velocity is equal to the ratio of displacement to time.

However, this equation only gives us the average velocity over a certain time interval. What if we want to know the velocity at a specific instant in time? For example, what if we want to know how fast the car was moving at exactly 1 second?

To answer this question, we need to use calculus. Calculus allows us to find the instantaneous velocity, which is the velocity at a specific point in time. To do this, we need to shrink the time interval Δ�Δt down to a very small (differential) size, so that it becomes ��dt. Similarly, we need to shrink the displacement Δ�Δx down to a very small (differential) size, so that it becomes ��dx. Then, we can define the instantaneous velocity as:

�=����v=dtdx​

where �v is the instantaneous velocity, ��dx is the differential change in position, and ��dt is the differential change in time. The symbol ���dtd​ means “the derivative with respect to time”, which is a concept from calculus that tells us how fast something is changing.

This equation tells us that instantaneous velocity is equal to the differential change in position divided by the differential change in time. This means that if we know how an object’s position changes with respect to time, we can find its velocity at any instant.

Position as a Function of Velocity

Another way to think about velocity and position is to reverse their roles. Instead of finding velocity from position, we can find position from velocity. That is, if we know how fast an object is moving at any instant, we can find where it is located at any instant.

To do this, we need to use another concept from calculus: integration. Integration is the opposite of differentiation, and it allows us to find the total change in something from its rate of change. For example, if we know how fast a car is moving at every instant, we can find how far it has traveled from its starting point.

Mathematically, we can write this relationship as:

�=∫���x=∫vdt

where �x is the position, �v is the velocity, and ��dt is the differential change in time. The symbol ∫∫ means “the integral with respect to time”, which is another concept from calculus that tells us how much something accumulates over time.

This equation tells us that position is equal to the integral of velocity with respect to time. This means that if we know how an object’s velocity changes with respect to time, we can find its position at any instant.

Conclusion

In this article, we have learned how velocity and position are related in one-dimensional motion. We have seen that:

• Velocity is the rate of change of position with respect to time.
• Position is the total change of velocity with respect to time.
• To find instantaneous velocity from position, we use differentiation.
• To find position from instantaneous velocity, we use integration.

These concepts are useful for describing and analyzing the motion of objects in one dimension.