I am thinking about the law of gravitation
The change in velocity that occurs within an interval of time is known as ACCELERATION.
Acceleration is the rate of change of velocity with time. It is a vector quantity. The rate of change of velocity can be positive or negative. The positive change of velocity is called acceleration while the negative change in velocity is called deceleration.
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Answer:
Periodic
Explanation:
A periodic (or repetitive) wave has continuously repeating pattern with characteristics such as amplitude, wavelength and frequency. In a periodic wave, a series of pulses that are evenly timed would be created. In other words, the wave pattern in a periodic wave repeats at regular intervals.
An example of a periodic wave is the sound from the strings of a violin.`
If there is no friction, then NO force is needed to keep an object moving. Go back and look at Newton's first law of motion again.