The dynamic vibration of hydraulic system is characteristic of instantaneous velocity, pressure and its oscillation.
So that's the definition of v, instantaneous velocity.
In addition, the instantaneous velocity is calculated, and its influencing factors are analyzed.
On the basis of Newton's second Law, a motion differential equation has been put forward, by which a formula to calculating instantaneous velocity has been obtained.
And now you will understand how we define the instantaneous velocity at time t which is different from an average velocity between two time intervals.