# 3D Velocity Of A Moving Object To A Stationary Object

• phys123
In summary, to calculate the change in speed of Object 2 towards Object 1, you will need to find Object 2's position and velocity. Then, find the unit vector pointing from Object 1 to Object 2 and take the scalar product of Object 2's velocity with that unit vector to find the component of velocity towards Object 1. This will give you the rate of change of the distance between the objects.
phys123
There are 2 objects. Object 1 is stationary and Object 2 is in motion. Object 1's position in the 3D world is (x=0,y=0,z=0). I have Object 2's velocity (also in x,y,z directions). I need to calculate the speed at which Object 2 is moving towards (or away from) Object 1. Keep in mind that this will not be Object 2's speed, because it is not moving directly towards Object 1. It is moving on it's own path, but I need to know the change in speed towards Object 1. Hope I explained that good enough, if not then ask. How can this be done?

You'll need Object 2's position. At any moment, find the component of Object 2's velocity parallel to its position vector with respect to the origin. That will be the rate of change of the distance between the Objects.

I do have Object 2's position, forgot to mention that. And what you are saying is exactly what I need to do. Can you go into detail on how I would calculate this? My physics isn't very strong

Not much physics here, just a bit of math. Find the unit vector pointing from 1 to 2--that gives you the direction. To find the component of 2's velocity in that direction, take the scalar product of the velocity with that unit vector.

To calculate the speed at which Object 2 is moving towards or away from Object 1, we can use the concept of relative velocity. This involves calculating the velocity of Object 2 relative to Object 1.

First, we need to find the vector distance between Object 1 and Object 2 at a specific point in time. This can be done by subtracting the coordinates of Object 1 (0,0,0) from the coordinates of Object 2 (x,y,z). This will give us a vector representing the distance between the two objects in the x,y,z directions.

Next, we can use the formula for relative velocity, which states that the relative velocity of Object 2 with respect to Object 1 is equal to the velocity of Object 2 minus the velocity of Object 1. In this case, we are only interested in the x,y,z components of the velocity, so we can ignore the z component of Object 1's velocity (since it is stationary).

Finally, we can calculate the magnitude of the relative velocity vector using the Pythagorean theorem, which will give us the speed at which Object 2 is moving towards or away from Object 1.

It is important to note that this method will only give us the instantaneous speed at a specific point in time. If we want to calculate the average speed over a longer period of time, we will need to use calculus to integrate the velocity over the desired time interval.

I hope this explanation helps. If you have any further questions, please let me know.

## 1. How is 3D velocity calculated for a moving object to a stationary object?

The 3D velocity of a moving object to a stationary object is calculated by dividing the distance traveled by the time taken to travel that distance. This calculation takes into account the speed and direction of the moving object relative to the stationary object.

## 2. What is the difference between 3D velocity and 3D speed?

3D velocity and 3D speed are often used interchangeably, but they are not the same. Velocity is a vector quantity that includes both speed and direction, whereas speed is a scalar quantity that only indicates the rate at which an object is moving.

## 3. Can the 3D velocity of a moving object change over time?

Yes, the 3D velocity of a moving object can change over time. This can happen if the speed or direction of the object changes, or if both change simultaneously. The change in velocity is directly related to the acceleration of the object.

## 4. How does the 3D velocity of a moving object to a stationary object affect collisions?

The 3D velocity of a moving object to a stationary object is a crucial factor in determining the outcome of a collision. If the velocities of both objects are similar, the collision will be more elastic. However, if there is a significant difference in velocities, the collision will be more inelastic.

## 5. What is the significance of 3D velocity in real-world applications?

The concept of 3D velocity is essential in various fields such as physics, engineering, and transportation. It is used to analyze the motion of objects in three-dimensional space and is crucial in understanding how objects move and interact with each other. 3D velocity is also used in computer graphics and animation to create realistic movements of objects.

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