Relative Velocity Calculator
Relative Velocity Calculator
Relative velocity describes how fast one object appears to move from the perspective of another. Enter both objects' velocities using a consistent sign convention (positive one way, negative the other), and this calculator computes how quickly object A is approaching or moving away from object B.
- The formula is v(A relative to B) = vA - vB, so if two cars move toward each other at 20 m/s and -15 m/s, their relative velocity is 20 - (-15) = 35 m/s - they close the distance between them at 35 m/s.
- Same-direction motion gives a smaller relative velocity, e.g. 20 m/s and 15 m/s in the same direction gives just 5 m/s of relative velocity - the gap between them changes slowly.
- Use a consistent positive direction for both velocities - this is the key to getting the sign of the result right.
How do I calculate relative velocity?
Subtract the second object's velocity from the first, using a consistent sign convention for direction: v(A rel. to B) = vA - vB.
What is the relative velocity of two cars approaching each other at 20 m/s and 15 m/s?
Using opposite signs for opposite directions: 20 - (-15) = 35 m/s.
Relative Velocity Calculator
Relative velocity describes how fast one object appears to move from the perspective of another. Enter both objects' velocities using a consistent sign convention (positive one way, negative the other), and this calculator computes how quickly object A is approaching or moving away from object B.
- The formula is v(A relative to B) = vA - vB, so if two cars move toward each other at 20 m/s and -15 m/s, their relative velocity is 20 - (-15) = 35 m/s - they close the distance between them at 35 m/s.
- Same-direction motion gives a smaller relative velocity, e.g. 20 m/s and 15 m/s in the same direction gives just 5 m/s of relative velocity - the gap between them changes slowly.
- Use a consistent positive direction for both velocities - this is the key to getting the sign of the result right.
How do I calculate relative velocity?
Subtract the second object's velocity from the first, using a consistent sign convention for direction: v(A rel. to B) = vA - vB.
What is the relative velocity of two cars approaching each other at 20 m/s and 15 m/s?
Using opposite signs for opposite directions: 20 - (-15) = 35 m/s.