These miniature,high speed, brushed DC gearmotors are intended for use at 6 V, though in general, these kinds of motors can run at voltages above and below this nominal voltage, so they should comfortably operate in the 3 – 9 V range (rotation can start at voltages as low as 0.5 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.
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If not suggest me any, i want to make a fast line following robot.
Also
2.is this motor a good choice for making soccer robot?
For line follower you can consider this: https://www.techshopbd.com/product-categories/motors/865/30-1-micro-metal-gearmotor-hp-6v-techshop-bangladesh
It's mentioned in the specification tab.