The phrase "a certain velocity" is correct and commonly used in written English.
It is used to refer to a particular speed or rate of movement, without specifying an exact numerical value. Example: The car was traveling at a certain velocity, allowing it to smoothly navigate the winding roads.
Combines and forage choppers are calibrated for a certain velocity range.
And the heavier they are, the faster they must be thrown: below a certain velocity, a stone will always sink.
The team performed numerical analyses, calculating the force generated by a given impacting mass at a certain velocity, and the resulting loss of atmospheric gases.
However, at a certain velocity the powder experiences a maximum charge whereas for higher velocities the charge subsequently drops.
The solution represents the probability density that a particle has a certain velocity and position at a given time.
Here, we propose that the local velocity fluctuation is generated by the sudden increase in the dynamic toughness at a certain velocity, for instance 2600 m/s in the (110) cleavage as reported in ref. 8.
In a final step, for each and every trial, the time at which the velocity-ratio time series reaches a certain velocity-ratio threshold can be determined.
When subjected to external perturbations, including either a moving load or a stationary one, the shell may be subjected to instability for flow velocities exceeding a certain critical velocity.
When a vehicle moves at high speed and if the speed exceeds a certain 'critical velocity', then quite intensive flexural waves travelling around the circumference of the tyre emerge from the trailing edge of the contact patch.
So a strictly localized wave has an indeterminate wavelength; its associated particle, while having a definite position, has no certain velocity.
The real value of the peak torque for the certain velocity was counted as a mean from series of movements.
