Is there a name for the rate of change of speed? (NOT the rate of change of velocity!)?

Question

I know that the rate of change of the velocity vector is called "acceleration".  Is there a name for the rate of change of SPEED?  (that is, the rate of change of the MAGNITUDE of the velocity vector)?

For example: Consider a particle moving in a circle of radius R, with a speed given by: |v| = kt.  It's easy to show that the magnitude of its acceleration is:

|a| = sqrt((kt)^4/R² + k²)

While on the other hand:

rate of change of speed = d|v|/dt = k

Is there a name (other than just "rate of change of speed") for this second quantity?

✰✰✰✰ Ms. Christmas ✰✰✰✰ · Accepted Answer

People normally call it acceleration too.
Here on Brazil, we call speed as "scalar velocity", and velocity as "vector velocity" or just "velocity".

If you think this way, you could call it scalar acceleration, ahaha!

But, yeah, there's no name. Physicists call it acceleration too.

Anonymous · Answer

I hope the person responds. In the meantime, your equation is correct. This applies when mass is constant and velocity does not approach the speed of light. A different equation is used in special relativity. Observed from an inertial reference frame, the net force on a particle is proportional to the time rate of change of its linear momentum: F = d[mv] / dt. Momentum is the product of mass and velocity. This law is often stated as F = ma (the net force on an object is equal to the mass of the object multiplied by its acceleration). This can also be stated as net force on an object is equal to its rate change of momentum Notice that the second law of motion only holds when the observation is made from an inertial reference frame.

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Is there a name for the rate of change of speed? (NOT the rate of change of velocity!)?

2 Answers