It subtracts one velocity vector from another to show what motion looks like from a moving frame of reference.
Relative Velocity Calculator
Compare two moving objects by finding object A's velocity as seen from object B.
Relative Velocity Calculator
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It subtracts one velocity vector from another to show what motion looks like from a moving frame of reference.
Live Result
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Example values are loaded
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Formula
Relative velocity is found with vector subtraction:
vA/B = vA - vB
vA = object A velocity
vB = object B velocity
vA/B = A relative to B
What the Relative Velocity Calculator Calculates
The Relative Velocity Calculator is built for moving observers, vehicle comparisons, collision setup, pursuit problems, and navigation frames. It subtracts one velocity vector from another to show what motion looks like from a moving frame of reference.
The calculator subtracts object B's velocity components from object A's components, then finds magnitude and direction.
- Compare cars, boats, aircraft, or runners.
- Set up collision-closing-speed calculations.
- Teach frames of reference.
Relative Velocity Calculator Formula
Relative velocity is found with vector subtraction: vA/B = vA - vB
Use the formula panel beside the calculator to keep the variables visible while you enter values.
- vA = object A velocity
- vB = object B velocity
- vA/B = A relative to B
How to Use the Relative Velocity Calculator
Enter the x and y components for object A and object B in the same coordinate system. The calculator keeps the fields focused on this specific problem so you do not have to adapt a generic velocity form by hand.
After you press Calculate, the result panel shows relative components, relative speed, and direction angle. Reset clears the example values so you can start a fresh scenario.
- Use consistent real-world measurements for the selected scenario.
- Check that time, area, mass, or temperature values are positive where the formula requires them.
- Read the step-by-step substitution before using the final number in homework, design notes, or planning.
Relative Velocity Calculator Example
If A moves at (20, 0) m/s and B moves at (12, 4) m/s, A appears to move at (8, -4) m/s relative to B.
How to Interpret the Relative Velocity Calculator Result
The relative vector describes how object A moves from object B's point of view. A zero result means both objects share the same velocity.
The extra output rows give practical companion values so the answer is easier to compare against common units or planning targets.
Relative Velocity Calculator Assumptions and Limits
Both objects are described in the same coordinate axes and the calculation uses classical, non-relativistic velocity subtraction.
For professional engineering, safety, aviation, ballistics, medical, or project-management decisions, treat the result as a calculation aid and verify it against the standards used in your field.
Frequently Asked Questions
Answers to common questions about relative velocity calculations.
Changing to object B's frame removes B's own motion, so A's velocity is vA - vB.
Yes. If two objects move with the same velocity vector, they are at rest relative to each other.
The speed magnitude is nonnegative, but the relative velocity components can be positive or negative.
Yes. Use opposite signs for opposite directions and the relative speed will show the closing rate.
No. Near light speed, relativistic velocity addition is required.